SSC CHSL Topic Wise Study Material – General Awareness – General Science
Contents
SSC CHSL Study MaterialSSC CHSL Previous PapersSSC CHSL Practice Workbook
Reference Corner
1.If in a motion,the axis of the rotation passes through an object then the motion is called SSC (10+2) 2017
(a)rotational motion
(b)circulatory motion
(c)spin motion
(d)oscillatory motion
2.Which among the following elements has highest electro negativity ? SSC (10+2) 2017
(a)Galium
(b)sodium
(c)argon
(d)caesium
3.Snake venom is highly modified saliva containing? SSC (10+2) 2017
(a)prototoxins
(b)neutrotoxins
(c)zootoxins
(d)electrotoxins
4.Which of the property of the sound is affected by change in air temperature? SSC (10+2) 2015
(a)Wavelength
(b)Amplitude
(c)Intensity
(d)Frequency
5.The common name of sodium bicarbonate? SSC (10+2) 2015
(a)baking powder
(b)soda ash
(c)baking soda
(d)soda lime
6.phycology is the study of ? SSC (10+2) 2015
(a)fungi
(b)lichens
(c)bacteria
(d)algae
7. A metal ball and a rubber ball, both having the same mass, strike a wall normally with the same velocity. The rubber ball rebounds and the metal ball does not rebound. It can be concluded that SSC (10+2) 2014
(a) both suffer the same change in momentum
(b) the initial momentum of the rubber ball is greater than that of the metal ball
(c) the rubber ball suffers greater change in momentum
(d) the metal ball suffers greater change in momentum
8. If the phase difference between two points is 120° for a wave with velocity of 360 m/s and frequency 500 Hz, then path difference between the two points is SSC (10 + 2) 2014
(a) 12 cm
(b) 24 cm
(c) 1 cm
(d) 6 cm
9. If a body moves with a constant speed in a circle SSC (10+2) 2014
(a) no acceleration is produced in it
(b) its velocity remains constant
(c) no work is done on it
(d) no force acts on it
10. The waves used in sonography are SSC (10 + 2) 2014
(a) sound waves
(b) ultrasonic waves
(c) microwaves
(d) infra-red waves
Answers
1. (c)
2. (c)
3. (c)
4. (d)
5. (c)
6. (d)
7. (c)
8. (b)
9. (c)
10. (b)
Physics
Physics is the study of nature and its laws. The word physics has been derived from a Greek word physics which means nature. Physics is one of the oldest academic disciplines, perhaps the oldest through its inclusion of astronomy.
Units
Measurement of any physical quantity involves comparison with a certain basic arbitrarily chosen and widely accepted reference standard called unit.
Scalar Quantities
Physical quantities which have magnitude only and no direction are called scalar quantities.
e.g., Mass, speed, volume, work, time, power, energy etc.
Vector Quantities
Physical quantities which have magnitude and direction both and which obey triangle law are called vector quantities
e.g., Displacement, velocity, acceleration, force, momentum, torque etc.
Displacement
» The difference between the final and the initial position of an object is called displacement. It may be positive, negative or zero.
» It is a vector quantity which has both magnitude and direction. Its unit is also metre.
Speed
» Speed is the distance covered by a moving body in unit time.
» It is a scalar quantity. It is always equal to or greater than magnitude of the velocity.
Velocity
» The rate of change of distance is called velocity.
» Velocity is a vector quantity, which has both magnitude and direction. Its unit is m/s.
» It may be positive or negative.
Acceleration
» It is the rate of change of velocity. Its SI unit is m/s². It is a vector quantity.
» When the velocity of a body increases with time then its acceleration is positive and if velocity decreases with time then its with time then its acceleration is negative.
» If velocity of a body is decreasing, then the acceleration is called retardation or deacceleration.
» Acceleration of an object is zero, if it is at rest or moving with uniform velocity.
Projectile Motion
» When a particle is so projected that it makes certain angle with horizontal, then the motion of the particle is said to be projectile.
» Path of projectile is a parabola.
» To achieve maximum range the body should be projected at an angle of 45°. Therefore, a long jumper takes jump at an angle of 45°
» To achieve maximum height the body should be projected at angle of 90°.
» When a body is dropped freely from the top of the tower and another body is projected horizontally from the same point’, both will reach the ground at the same time.
» If we throw two balls of different masses in horizontal direction, then they will again reach oh earth at the same time because both the balls will have zero velocity in vertical direction.
Circular Motion
When an object moves along a circular path, then its motion is called circular motion as motion of top etc. If an object moves along a circular path with uniform speed, its motion is called uniform circular motion.
Centripetal Force
A body performing circular motion is acted upon by a force which is always directed towards the centre of the circle. This force is called centripetal force. Any of the forces found in . nature (such as frictional force, gravitational force, electrical force, magnetic force etc) may act as a centripetal force.
Cyclist bends his body towards the centre on a turn while turning to obtain the required centripetal force.
Generally, in rain the scooter slips at the turning of a road because the friction between tyre and road is reduced. Due to this necessary centripetal force is not provided. Roads are banked at turns to provide the required centripetal force for taking a turn.
Centrifugal Force
In applying the Newton’s laws of motion, we have to consider some forces which cannot be assigned to any object in the surrounding. These forces are called Pseudo force or inertial force. Centrifugal force is such a Pseudo force. It is always equal and opposite to centripetal force.
[Cream separator, centrifugal drier etc, work on the principle of centrifugal force.]
Newton’s Laws of Motion
There are three Law of Motion.
First Law
» “Every body retains its state of rest or state of motion, until an external force is applied on it.” This law is also known as law of inertia or law of Galileo.
» First law gives the definition of inertia. Inertia is the virtue of a body due to which it tries to retain its state. Inertia is of three types
(i) Inertia of rest
(ii) Inertia of motion
(iii) Inertia of direction
* A person sitting in a moving car falls forward, when the car stops; suddenly. This is because the feet of the passenger comes to the rest along with the car, but the upper part of his body, due to inertia of motion, tends to remain in motion.
* The dust particle come out. from a carpet, when it is beaten with a stick due to their inertia of rest.
Second Law
“The force applied on a body is equal to the product of mass of the body and the acceleration produced in it F = ma.”
The second law of motion gives the definition of force.
Third Law
“Every action have equal and opposite reaction.” Action and reaction always act on the different bodies.
* On firing the bullet, the gunner is pushed to backward direction.
* When the boatman is jumped from the boat, the boat is pushed back.
* In a rocket, gases are ejected with a great speed from the rocket backwards and rocket is pushed forwards.
* While swimming, a person pushes the water backwards (action). The water pushes the swimmer forward with the same force (reaction).
Linear Momentum
» The product of the mass and the velocity of a body is called the linear momentum of the body.
» A heavier body has a larger linear momentum than a lighter body moving with the same velocity.
» In the absence of external forces, the total linear momentum of the system remains conserved.
Impulse
» If a force acts on a body for a very short time Δt, then the product of force and time is called the impulse.
» Its SI unit is N-s or kg-m/s.
Equilibrium
If the resultant of all the forces acting on a body is zero then the body is said to be in equilibrium. If a body is in equilibrium, it will be either at rest or in uniform motion. If it is at rest, the equilibrium is called static, otherwise dynamic.
Static equilibrium is of two types .
Stable and unstable equilibrium.
Friction
It we slide or try to slide a body over a surface, the motion is resisted by a bonding between the body and the surface. This resistance is called frictional force.
Energy
» It is defined as capacity of doing work.
» Its unit is joule in SI and erg in CGS system.
Mechanical energy is in two forms
Kinetic energy and potential energy.
Kinetic Energy
» It is the energy possessed by a body by virtue of its motion.
» If a body of mass m is moving with velocity ν, then kinetic energy. KE = 1/2 mν²
» When momentum is doubled, kinetic energy becomes four times.
* Kinetic energy of air is used to run wind mills.
* Kinetic energy of running water is used to run the water mills.
* A bullet fired from a gun can pierce a target due to its kinetic energy.
» If a body is moving in horizontal circle then its kinetic energy is same at all points, but if it is moving in vertical circle, then the kinetic energy is different at different points.
Potential Energy
» It is the energy possessed by a body by virtue of its position.
» Suppose a body is raised to a height h above the surface of the earth, then potential energy of body
U =mgh.
» When a body is falling downwards, then its potential energy goes on changing to kinetic energy.
* The potential energy of the wound spring of a clock is used to drive the hands of the clock.
* The potential energy of water in dams is used to run turbines in order to produce electric energy using the generators.
Law of Conservation of Energy
According to the law of conservation of energy, “energy can neither be created nor be destroyed but it can be transformed from one form to another”.
The sum of all kinds of energies in an isolated system remains constant at all times.
Transformation of Energy
* In a heat engine, heat energy changes into mechanical energy.
* In the electric bulb, the electric energy is converted into light energy.
* In burning coil, oil etc., the chemical energy changes to heat energy.
* In solar cell, solar energy changes into electrical energy.
* In playing sitar, mechanical energy changes into sound energy.
* In microphone, sound energy changes into electrical energy.
* In loud speaker, electrical energy changes into sound energy.
* In battery, chemical energy changes into mechanical energy.
Gravity
» It is the force by which earth attracts a body towards its centre.
» The acceleration due to gravity is the rate of increase of velocity of a body falling freely towards the Earth. It is represented by g =GMe/Re2
Where, Me is the mass of earth and Re is the radius of Earth.
» The value of g at the surface of earth is 9.8 m/s²
» Earth is surrounded by an atmosphere of gases due to gravity.
» The value of g on the Moon is 1/6th of that on the Earth.
Escape Velocity
» The minimum velocity of the body that should be given to the body to enable it to escape away from Earth’s gravitational field is called escape velocity. Its value on the Earth’s surface is 11.2 km/s.
» The value of the escape velocity of a body does not depend on its mass. Its value on the Moon surface is 2.38 km/s. So, there is no atmosphere around the moon.
» Escape velocity is √2 times the orbital velocity.
» Satellites are launched with the escape velocity as needed.
Pressure
» It is defined as force acting normally on unit area of the surface.
Pressure =Normal force /Area
» Its unit is N/m² also called Pascal. It is a scalar quantity.
» Atmospheric pressure decreases with altitude. This is why
(i) it is difficult to cook on the mountain
(ii) the fountain pen of a passenger leaks in aeroplane at height.
» Atmospheric pressure is measured by barometer. The slow rise. in the barometric reading, is the indication of clear weather.
» Sudden fall in barometric reading is the indication of storm.
» Slow fall in barometric reading is the indication of rain.
Pascal’s Law
» The pressure exerted anywhere at a point of confined fluid is transmitted equally and undiminished in all directions throughout the liquid.
» Hydraulic lift, hydraulic press, hydraulic brake work on the basis of Pascal law.
Surface Tension (T)
» It is the force (F) acting normally an unit length (l) of imaginary line drawn on the surface of liquid.
i.e..T=F/l
» Its unit is N/m.
» The surface tension decreases with rise in temperature and becomes zero at the critical temperature.
» Due to the surface tension, rain drops are spherical in shape.
* Warm soup is tasty because at high temperature its surface tension is low and consequently the soup spreads on all part of tip tongue.
* When kerosene oil is sprinkled on water, its surface tension decreases.
Capillarity
» The phenomenon of rise or depression of liquids in a capillary tube is called capillarity.
» The liquids which wet glass for which the angle of contact is acute rise up in the capillary tube, while those which do not wet glass, for which the angle of contact is obtuse are depressed down in the capillary.
The angle of contact is zero for pure water and clean glass. It is 90° for water and silver, 8° for ordinary water and glass and 135° for mercury and glass.
Some Practical Examples of Capillarity
* The kerosene oil in a lantern and the melted wax in a candle, rise in the capillaries formed in the cotton wick and thus they are burnt.
* Writing nib is split in the middle so that a fine capillary is formed in it. When it is dipped in ink the ink rises in the capillary.
* The water given to the fields rises in the innumerable capillaries formed in the stems of plants and trees and reaches the branches and the leaves.
* The farmers plough their fields after rains so that the capillaries formed in the soil are broken and the water remains in the lower layers of the soil.
Buoyancy
» The upward force exerted by a fluid on the immersed body is called buoyant force or upthrust. The upthrust acts at the centre of gravity of the liquid displaced by the submerged part of the body that is called the centre of buoyancy.
» Buoyant force depends on the density of the fluid and not on the density of body and acts on centre of gravity of fluid.
Archimede’s Principle
When a solid body is immersed wholly or partially in a liquid, then there is same apparent loss in its weight. This loss in weight is equal to the weight of the liquid displaced by the body.
Law of Floatation
Whenever a solid body is dipped into a fluid, the fluid exerts force of buoyancy on it, if the force of buoyancy equals to weight of the solid, the solid will remain in equilibrium. This is called Floatation.
Density
» The density of a substance (d) is defined as the ratio of its mass (M) to its volume (V).
i.e..d=M/V
Its unit is kg/m³.
» Density of water is maximum at 4° C.
» The relative density is defined as the ratio of the density of the substance to the density of water at 4° C.i. e.,Relative density = Density of substance/Density of water at 4° C
» Relative density has no unit.
» Relative density is measured by hydrometer.
» If ice floating in water in a vessel melts, the level of water in the vessel does not change.
» The density of sea water is more than that of normal water. This explains why it is easier to swim in sea water.
Simple Pendulum
» It is a heavy point mass suspended from a rigid support by means of an elastic inextensible string.
» The maximum time period of a simple pendulum is 84.6 min.
» A pendulum clock goes slow in summer and fast in winter.
» If a simple pendulum is suspended in a lift descending down with acceleration, then time period of pendulum will increase. If lift is ascending, then time period of pendulum will decrease.
» If a lift falling freely under gravity then the time period of the pendulum will be infinite.
» At Moon, the time period of simple pendulum increases, because acceleration due to gravity at moon is very less.
Waves
» A wave is a disturbance which propagates energy from one place to the other without the transport of matter.
These are of two types
(i) Mechanical waves
(ii) Electromagnetic waves
Mechanical Waves
» The waves which require material medium (solid, liquid or gas) for their propagation are called mechanical waves or elastic waves.
These are of two types
(i) Longitudinal waves
(ii) Transverse waves
Electromagnetic Waves
» The wave which do not require medium for their propagation i.e., which can propagate even though the vacuum are called electromagnetic wave. They propagate as transverse wave.
» The wavelength range of electromagnetic wave is 10-4 m to 104 m.
» Cathode rays, canal rays, α-rays, β-rays are not electromagnetic waves. Light and heat are examples of electromagnetic waves.
Sound Waves
» It is longitudinal mechanical waves.
» The longitudinal mechanical waves which lie in the range 20 Hz to 20000 Hz are called audible or sound waves.
» These are sensitive to human ear.
» The longitudinal mechanical waves having frequencies less than 20 Hz are called infrasonic. These are produced by earthquakes, volcanic, eruption, ocean waves and elephants and whales.
» The longitudinal mechanical waves having frequencies greater than 20000 Hz are called ultrasonic waves.
» Ultrasonic waves are used for sending signals, measuring the depth of sea, cleaning clothes and machinery parts of clocks, removing lamp shoot from chimney of factories and in ultrasonography.
Speed of Sound
» Speed of sound is maximum in solids and minimum in gases.
» Speed of sound in air is 332 m/s, in water is 1483m/s and in iron is 5130 m/s.
» Speed of sound basically depends upon elasticity and density of medium.
» Speed of sound remains unchanged by the increase or decrease of pressure.
» The speed of sound increases with the increases of temperature of the medium. The speed of sound in air increases by 0.61 m/s when the temperature is increased by 1°C.
» The speed of sound is more in humid air than in dry air because the density of humid air is less than the density of dry air.
Heat
» It is a form of energy Which produces the sensation of warmth in us.
» It is due to the kinetic energy of the molecules constituting the body.
» Its units are calorie (cal), kilocalorie (kcal) or joule (j).
Temperature
» It is the measurement of hotness or coldness of a body.
» When two bodies are placed in contact, heat always flows from a body at higher temperature to the body at lower temperature.
» An instrument used to measure the temperature of a body is called a thermometer.
Specific Heat
» It is the amount of heat required to raise the temperature of a unit mass of the substance of 1°C. Its unit is J/kg°-C.
» For most substances, the specific heat increases with rise in temperature and assumes a constant value at high temperature.
» The specific heat of water, however decreases with rise in temperature from 0°C to about 40° C after which it increases with temperature.
» Mercury has low specific heat.
» Hot water burns are less severe than that of steam burns because steam has high latent heat.
» Ice at 0°C appears colder than that water at 0°C, because ice takes more heat
Transmission of Heat
» Transfer of heat from one place to other place is called transmission of heat.
There are three processes, by which transmission of heat
takes place
(i) Conduction
(ii) Convection
(iii) Radiation
Conduction
» In this process heat is transferred without bodily movement of the particles of medium.
» In this process path of heat transfer is irregular. In solid, transmission of heat takes place by conduction process.
» Mercury though a liquid is heated by conduction and not by convection.
Convection
» In this process heat is transferred by the bodily movement of particles of the medium due to difference in densities of different parts of the medium.
» In liquid and gases transmission of heat takes place by convection process. This process is also slow.
» The chimney used in kitchen or in a factory is based on the convection. In rooms ventilators are provided to escape the hot air by the process of convection.
Radiation
» It is the quickest way of transmission of heat in which there is no need of medium for transfer of heat.
» Heat from the sun reaches the earth by radiation.
» In this process, heat is transferred at the speed of light.
Perfectly Black Body
A perfectly black body is one which absorbs completely all the radiations falling on its surface, whatever be the wavelength.
Light
» It is the radiation which makes our eyes able to see the object. Its speed is 3 x 108 m/s.
» It is the form of energy. It is a transverse wave.
» It represents the phenomenon of reflection, refraction, interference, diffraction, scattering and polarization.
Reflection of Light
» The return of light into the same medium after striking a surface is called reflection.
There are two laws of reflection
* The angle of incidence is always equal to angle of reflection.
* The incident ray, normal and reflected ray all lie in the same plane.
Uses of Mirrors
* Plane mirrors are used as looking glass.
* Concave mirror is used as shaving mirrors, used by doctors, shades of table lamp, for search lights.
* Convex mirror is used as back view mirrors in vehicles, in street lamps etc.
Refraction of Light
» When a ray of light passes from one medium to other, it bends from its path. This phenomenon of bending of light is called as refraction of light. When a ray of light travels from one medium to another the wavelength and velocity of light change but the frequency does not change.
* Twinkling of stars is based upon refraction.
* Due to refraction, rivers appear shallow, coin in a beaker filled with water appears raised, pencil in the beaker appear broken.
* At sunset and sunrise, due to refraction, sun appears above horizon while it is actually below horizon
* The duration of day appears to be increased by nearly 4 min due to atmospheric refraction.
* Writing on a paper appears lifted when a glass slab is placed over the paper.
» The refractive index of a medium is maximum for violet colour of light and minimum for red colour of light.
» Refractive index decreases with rise in the temperature.
» If the angle of incidence in denser medium is greater than critical angle (C), then the ray is reflected back into the first rarer medium, this phenomenon is called total internal reflection.
In desert, the phenomena of mirage occurs due to total internal reflection.
Scattering of Light
» When light pusses through a medium, in which particles are suspended, whose sizes are of the order of wavelength of light, then light on striking these particles, deviated in different directions.
This phenomenon is called scattering of light.
» Red colour of light is scattered least and violet colour of light is scattered most. Therefore, danger signals are of red colour.
» Blue colour of sky is due to scattering of light. The brilliant red colour of rising and setting sun is due to scattering of light.
» Clouds appear white due to scattering of light.
» Sky appears black to Astronaut from the space.
» The air bubbles in glass paper weight appear silvery white due to total internal reflection.
» Sparkling of diamonds is due to multiple total internal reflection taking place inside the diamond.
Optical Fibre
* It is a device based on total internal reflection by which a light signal can be transferred from one place to the other with a negligible loss of energy.
* It is used in testing the internal called the endoscopy parts of the human body and transmitting and receiving the electrical signal after converting it into the light signal.
Dispersion of Light
» When a narrow beam of light is incident on a prism, the emergent beam is not only deviated but at the same time splits up into a coloured band of seven colours. This phenomenon is called dispersion of light.
» The seven colours of band are violet, indigo, blue, green, yellow, orange and red.
» Violet colour deviates through maximum angle and red colour deviates through the minimum angle.
» Red, green and blue are called primary colours or basic colours.
» Polarisation is the only phenomenon which proves that light is a transverse wave.
» The layer of kerosene over water surface appear coloured in the presence of sunlight due to proper interference of light.
» Rainbow formation is caused due to total internal reflection and refraction by dispersion of light.
Human Eye
» It is an optical instrument just like a photographic camera. It forms the real image of the object on retina of the eye.
» For the normal eye, the range of vision is from 25 cm to infinity.
Defects of Vision
There are three types of defects vision.
1. Myopia
» In this case, the person cannot see the distant object.
» Image is formed before the retina.
» Concave lens is used for correcting myopia.
2. Hypermetropia
» In this case, the person cannot see near object.
» Image is formed behind the retina.
» Convex lens is used for correcting hypermetropia.
Astigmatism
In this case, the curvature of cornia becomes irregular and image is not clear. Cylindrical lens is used for correcting astigmatism.
3. Presbyopia
» In old age the power of accommodation of the eye lens decrease, therefore, neither near nor distant objects are clearly seen.
» Presbyopia can be removed by using bifocal lenses.
Electricity
Charge
» It is something that a body attains when it loses or gains the electrons.
» The positive and negative labels and sign for electric charge were chosen arbitrarily by Benjamin Franklin. Similar charges repel each other and opposite charges attract each other.
» Charge is a scalar quantity and its SI unit is coulomb C.
» Electricity is associated with the- charge.
» Conductors are those substances which allow passage of electrical charge to flow through them and have very low electrical resistance.
» Metals like silver, iron, copper are conductor.
» Human body and earth act like a conductor. Silver is the best conductor.
» Insulators are those substances which do not allow passage of charge through themselves. Rubber, wood, mica, glass, ebonite are insulators.
Electric Fuse
» It is a small conducting wire of alloy of copper, tin and lead having low melting point and high resistance.
» It is a protective device used in series to prevent the damage due to excess flow of current.
» All electric appliances like bulbs, fans etc are connected in parallel across the live wires and the neutral wires.
Electric Cell
» Electrical cell is a device which converts chemical energy into electrical energy.
Electrical cells are basically of two types (i) Primary cell (ii) Secondary cell
» Primary cell In primary cell electrical energy is obtained from the irreversible chemical reaction taking place inside the cell. After completing discharge, primary cell becomes unserviceable. Examples Voltaic cell, Leclanche Cell, Daniel Cell, Dry Cell etc.
Secondary Cell
Secondary cells can be charged again and again. Acid and alkali accumulators are the types of Secondary cells.
Magnets
» The material which can attract the magnetic substances (such as cohalt, iron and nickel) is called a magnet and the property of attracting the magnetic substance by a magnet is called magnetism.
» The magnets which do not lose their magnetism with normal treatment are called permanent magnets.
» The materials which retain their magnetism for a long time are called hard magnetic materials. When a magnet is freely suspended, it aligns itself in the geographical North-South direction.
» When poles of two magnets are brought close together, they exert force on each other.
» Similar poles repel each other and dissimilar poles attract each other.
» Permanent’ magnets are made of steel, and temporary magnets or electromagnets are made of soft iron.
X-rays
» These rays were discovered by Roentgen.
These rays are electromagnetic in nature.
» X-rays travels in straight line.
» Speed of X-rays is equal to speed of light. These are not deflected by electric and magnetic fields.
» These produce illumination on falling on fluorescent substances.
» X-rays shows photoelectric effect.
» X-rays are used in surgery, radio-therapy, engineering department and searching.
Chemistry
Matter
» Matter is anything which has mass and occupies space.
» It exists in five phases, viz, solid, liquid, gas, plasma, Bose-Einstein condensate. Out of which the former three are commonly seen.
Solids
» They have definite volume and shape.
» They are incompressible and have strongest intermolecular interactions.
» They are very dense as compared to liquid and gas. Examples are wood, stone, iron etc.
Liquids
» These have definite volume but no definite shape. They take the shape of the vessel in which these are kept.
» They can flow so considered as fluids. Examples of liquids are milk, water, mercury etc.
Gases
» These have neither definite volume nor definite shape. These take the shape and volume of the container in which these are filled.
» These are highly compressible.
» These can flow so considered as fluids. Examples are air, oxygen, nitrogen.
» Solid, liquid and gases are inter convertible by changing the conditions of temperature and pressure.
Melting Point
» It is a temperature at which a substance converts from its solid state to liquid state. Melting point of ice is 0° C.
» Melting point decreases in the presence of impurity.
Boiling Point
» It is a temperature at which vapor pressure of a liquid becomes equal to atmospheric pressure.
» It is different at different places.
» Boiling point of water at normal conditions is 100° C
* It usually decreases at high altitudes, that’s why at high altitudes, the boiling point of water is less than 100°C and more time is required to cook a food.
* Boiling point of water in pressure cooker is high due to high pressure and hence, less time is required to cook the food.
* Boiling point increases in the presence of impurity.
Evaporation
» It is the process of conversion of a liquid into vapors at any temperature below its boiling point.
» It increases with increase in surface area and temperature.
» It produces cooling. That’s why we feel cool when some nail polish remover or spirit is kept on our palm.
Sublimation
» It is the process of transition of a substance from the solid phase to the gas phase without passing through an intermediate liquid phase.
» It is used to separate a sublimate (substance undergoing sublimation like camphor, naphthalene, ammonium chloride etc.) from non-sublimate.
Atom
» it is the smallest particle of matter that takes part in chemical reactions, (by Dalton’s atomic theory).
» It can neither be created nor destroyed (law of conservation of mass given by Lavoisier).
» It does not exist in free state and has a fixed atomic mass e.g., iron (Fe), gold (Au), silver (Ag) etc.
Molecules
» These are the smallest part of the matter that exist in free state.
» They are formed by the joining of two or more atoms in fixed ratio (law of multiple proportions given by Dalton)
» They have fixed molecular mass which is obtained by adding the atomic masses, of all the atoms present in a molecule.
e.g., water (H2O), ammonia (NH3), carbon dioxide (C02) etc.
Elements
» They contain only single type of atoms.
» Elements known at present are 118. Out of which 94 are natural.
» Elements which are liquid at room temperature are mercury (Hg) and bromine (Br).
» Elements which become liquid at a temperature slightly above the room temperature (303 K), are gallium (Ga) and cesium (Cs).
» Examples (of elements) are diamond, graphite, sulphur (S8), phosphorus (P4), ozone (03), oxygen (O2) etc.
Compounds
» These contain more titan one kind of atom. These cannot he separated into constituent atoms by simple physical methods.
» Their examples are silica (Si02), water (H20), sugar (C12H22O11), salt (NaCl) etc.
Mixtures
» These are obtained by mixing two or more substances in any proportion.
» Mixtures can be homogeneous, i.e., have uniform composition throughout (e. g., salt solution, sugar solution, air, true solutions etc.) or heterogeneous, i.e., have non-uniform composition (e. g., mixture of salt and sugar, colloidal solutions etc).
Solutions or True Solutions
» These are homogeneous mixtures of two or more substances. A solution contains two components: solute (in less quantity) and solvent (inTflbre quantity).
» Concentration of solution may be expressed by percentage, mole fraction, parts per million, gram per litre, molarity morality, normality etc
Colloidal Solutions
» These are heterogeneous mixtures.
» These contain two phases, Le., dispersed phase and dispersion medium.
» These can scatter light because of the presence of large solute particles, i.e., they show Tyndall’s effect and Brownian movement.
Blue colour of sky is also due to scattering of light by dust particles suspended in air.
» They are separated by special technique like centrifugation.
» They are of following types on the basis of dispersed phase and dispersion medium.
» Colloidal solutions are coagulated by adding an electrolyte.
» Colloidal solutions are purified by dialysis, which is also used in the purification of blood with the help of artificial kidney machine.
Coagulation found its use in purification of water by alum, stoping bleeding by FeCl3 formation of delta at the junction of sea and river.
Centrifugation
» It is based upon the principle that the denser particles are forced to the bottom and the lighter particles stay at the top when spun rapidly.
» It is used in diagnostic laboratories for blood and urine tests, in dairies and home to separate butter from cream, in washing machine to squeeze out water from wet clothes.
Physical Change
» It is the change which only affect the physical properties like colour, hardness, density, melting point etc., of matter.
» It does not affect the composition and chemical properties of matter.
Examples of physical changes are crystallisation, sublimation, boiling, vaporisation, cutting of trees, dissolving common salt in water, etc
Chemical Change
» These affect the composition as well as chemical properties of matter and result in the formation of a new substance.
» Their examples are burning of fuel, burning of candle, electrolysis of water, burning of paper, photosynthesis, ripening of fruits etc.
Ideal and Real Gases
» Ideal gases follow gas laws in all conditions of temperature and pressure.
» Real gases follow gas laws only at high temperature and low pressure.
Atomic Structure and Radioactivity
Constituents of Atom
» These are electrons, protons and neutrons.
» Atom contains a central nucleus surrounded by a cloud of negatively charged electrons.
Electron (-1e0)
» It is a fundamental particle of atom. Its antiparticle is positron.
» It revolves around the nucleus.
» It has mass 9.1 x 10-31 kg or 0.00054 u.
» It has charge – 1.6 x 10-19 C (by Millikan oil drop experiment).
» It was discovered by JJ Thomson.
Proton (1p1)
» It was discovered by Rutherford.
» It is positively charged.
» If is present in the nucleus.
» It has charge + 1.6 x 10-19 C and mass
1.672 x 10-27 kg or 1.00727 u.
» It has mass 1836 times that of the electron.
Neutron (0n1)
» It was discovered by Chadwick.
» It has zero charge and 1.674x 10-17 kg or 100867 u mass.
» It is present inside the nucleus. Its antiparticle is antinutrino.
Cathode Rays
» These were discovered by JJ Thomson.
» These originate from cathode and travels in a straight line towards anode.
» Cathode rays cause mechanical motion, i.e., they consists of material particles.
» These rays carry negative charge and generate X-rays.
Anode rays
» These were discovered by Goldstein, (also called positive rays.)
» These do not originate from anode.
» These are positively charged and have velocity less than cathode rays.
* Hydrogen is the only atom in which neutrons are not present.
* Electromagnetic forces bind electrons with the nucleus.
* Atom having same number of electrons and protons is neutral. If electrons are less than proton, the atom carries positive charge and if electrons are more than proton, the atom carries negative charge.
* According to de-Broglie, all particles have wave nature.
Atomic Number (Z)
» It is equal to the number of protons.
» It is equal to the number of electrons in neutral atom.
» It is written as a subscript to the left of the symbol of . the atom e.g., 6C here, 6 is the atomic number of carbon (C).
Mass Number (A)
» It is equal to the sum of number of protons and number of neutrons.
» It is written as superscript to the right of the symbol of the atom, e.g., C12 here, 12 is the mass number of carbon (C).
Mass number = number of protons + number of neutrons = atomic number + number of neutrons = number of electrons + number of neutrons (in ease of neutral atom)
Isotopes
» These have same atomic number but different mass number. Their examples include isotopes of hydrogen i. e.,, 1H1, (protium),, 1H2 or D (deuterium) and 1H3 or T (tritium) T is radioactive.
» Isotopes of polonium are maximum.
Hydrogen (1H1) is the lightest isotope and lead-208 is the heaviest isotope (with mass 207.974).
Isobars
» These have the same mass number but different atomic number.
» 18Ar40 , 19K40 , 20Ca40 are isobars.
Isotones
» These have same number of neutrons, e.g.,1H3 and 2He4 as both have two neutrons.
Radioactivity
» It was discovered by Henry Becquerel but term radioactivity was given Madam Curie. It is the process of spontaneous disintegration of nucleus and is measured by Geiger counter.
» It is a nuclear phenomenon, thus remains unaffected by external factors like temperature, pressure etc.
» It involves emission of α ,β ,γ -rays/particles and has units Curie, Becquerel, Rutherford.
Alpha (α) – particle
» These are positively charged helium nuclei (2He4)2+. They have + 2 unit charge and 4 u mass.
» They have low penetrating power but very high ionising power and kinetic energy.
Beta (β) – particle
» These are negatively charged electrons (-1e0) and have -1 unit charge and 0 mass.
» These are more dangerous than α-rays.
» These have high penetrating power as compared to ‘α-rays.’
Gamma (γ) – rays
» These are electromagnetic radiation and have very high penetrating power.
» These have low, ionising power and kinetic energy.
» Their emission does not affect the position of nuclei in the Periodic Table.
Nuclear Fission
» It is a process in which a heavy nucleus is broken down into two or more medium heavy fragments.
» It is usually accompanied with the emission of neutrons and large amount of energy. It is used in nuclear reactor and atom bomb.
Nuclear Reactor
» It is a device that is used to produce electricity and permits a controlled chain nuclear fission.
» It contains fules e.g., 92U235, moderator
(e. g., graphite and heavy water, D20) to slow down neutrons and control rods (made up of boron steel or cadmium) to absorb neutrons.
» It may also contain liquid sodium as coolant.
Half-life Period
It is the time in which a radioactive substance remains half of its original amount.
Atom Bomb
It is based on uncontrolled nuclear fission. It contains 235U or 239Pu as fuel.
Nuclear Fusion
» It is a process which involves fusion of two or more lighter nuclei to give a heavier nuclei.
» It occurs only at extremely high temperature (> 106 K), so also called thermonuclear reactions.
» It is used in hydrogen bomb. Energy of Sun is also a result of a series of nuclear fusion reactions.
Hydrogen Bomb
» It contains a mixture of deuterium oxide (D20) and tritium oxide (T20) in a space surrounding an ordinary atom bomb.
Radiocarbon Dating
» It is used in determining the age of carbon bearing materials such as wood, animal fossils etc.
» It is based on the concentration of C12 and C14 isotopes.
Chemical Bond
» It is formed by elements to complete eight electrons in their outer shell i.e., to complete their octer.
» It results in decrease in energy and increase in stability.
Valency
» It is the number of electrons taking part in bonding (i.e., bond formation).
» It generally increases from 1 to 7 in a period with respect, to hydrogen but with respect to oxygen, it first increases from 1 to 4 and then decreases to 1.
Ions
» These are of two types cation and anion. Cations are formed by the loss of electrons and carry positive charge, e.g., Na+, Mg2+. Anions are formed by the gain of electrons.i.e., carry negative charge e.g., Cl–, F– etc.
Catalysis
» It was discovered by Berzelius.
» It is a term, used for the reactions/ processes which occur in the presence of certain substances that increase the rate of the reaction without being consumed. Such substances are called catalysts.
Oxidation
» It involves addition of oxygen or any other electronegative element like fluorine (F), chlorine (Cl), nitrogen (N) etc.
» It involves removal of hydrogen (H) or any other electropositive element like sodium (Na). It involves loss of electrons i.e., increase in the positive charge of ion.
Reduction
» It involves addition- of hydrogen or any other electropositive element.
» It involves removal of oxygen or any other electronegative element.
» It involves gain of electron, i. e., decrease in oxidation state.
Redox Reactions
» In such reactions, oxidation and reduction occur simultaneously.
» These are called disproportionation reaction when the same element is oxidised as well as reduced.
Acids
» These are the substance, which have sour taste and turn blue litmus red.
» These are the substance which gives H+ ions in their aqueous solution.
» These in aqueous solution are conductor of electricity.
» Generally, most of the acids contain hydrogen pickles are always.
» Kept in glass jar because acid present in them reacts with the metal of metallic pot.
Aqua-regia
It is a mixture of concentrated hydrochloric acid (HCl) and concentrated nitric acid (HN03) in the ratio of 3 :1. It is used to dissolve noble metals like gold and platinum.
Bases
These are the substances, which have bitter taste and turn red litmus blue.
» Bases give OH– ion in their aqueous solution (Arrhenius concept)
Indicators
» These are the substances which give different colours in acid and base solutions.
» Some indicators and their colour in acid and base medium are
pH Value
» It is a measure of acidity or basicity of a solution.
» It is defined as the negative logarithm of the concentration in (mol/L) of hydrogen ions which it contains, i.e.,
pH =- log [H+] = log 1/[H+] or [H+]= 1 x 10-pH
» It is 7 for neutral solution, greater than 7 for basic solution and less than 7 for acidic solution.
» pH of some common substances are
Metals
» These are the elements which are hard, lustrous, ductile, malleable, sonorous and conductor of heat and electricity in their solid as well as molten state.
» These form oxide with air. These oxides are generally basic, but oxides of zinc and aluminium are amphoteric, i.e., have acidic as well as basic properties.
» These evolve hydrogen gas when reacts with water and acids.
» Metals which are highly reactive displace the less reactive metals from their salts. The order of reactivity is, potassium (K) > sodium (Na) > calcium (Ca) > magnesium (Mg) > aluminium (Al) > zinc (Zn) > iron (Fe) > lead (Pb) > hydrogen (H) > copper (Cu) > mercury (Hg) > silver (Ag) > gold (Au) (Thus, gold is less reactive metal).
* Mercury (metal) is liquid at room temperature.
* Sodium and potassium are soft and highly reactive metals. These react with air and water. That’s why these are kept in kerosene oil.
* Silver, gold and platinum do not react with air even on strong heating.
* Sodium and potassium burn in water while calcium floats over it.
* Copper(Cu) is the first metal used by man.
* Pb (lead) is a bad conductor of electricity.
* Ti is called strategic metal.
Non-metals
» These may be solid, liquid or gas (bromine is the only liquid non-metal).
» These are soft, non-lustrous, brittle, non-sonorous and non- conductor of heat and electricity.
» These have low melting and boiling points.
» These form oxides with oxygen which are generally acidic.
» Their examples include noble gases i.e., helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe) and some other p-block elements.
* Diamond is the hardest substance known.
* Iodine is lustrous.
* Melting point is very high for diamond and graphite.
* The order of hardness of some substances is diamond > corundum > topaz > quartz
Alloys
» These are mixtures of two metals or a metal and a non-metal. They have properties different from the main metal.
» Alloys of mercury are called amalgam.
Fuels and Flame
Fuels
» These are the substance which produce heat and light on combustion.
Some important gaseous fuels and their compositions are as follows
Flame
It is the hot part of fire and has three parts
Innermost region of flame
» It is black because of the presence of unburned carbon particles.
» It has the lowest temperature.
Middle region
It is yellow luminous due to partial combustion of fuel.
Outermost region
» It is blue (non-luminous) due to complete combustion of fuel.
» It is the hottest part of flame and is used by the Goldsmith to heat the gold.
* Water is a common fire extinguisher.
* In case of electric fires and oil fires, water cannot be used as an extinguisher as it is a conductor of electricity and oil being lighter comes above the water. Such fires are extinguished by carbon dioxide.
Hard Water
» It does not lather with soap.
It is of two types
Temporary Hard Water
» It contains bicarbonates of calcium and magnesium.
» It is converted into soft water by boiling or by adding calculated quantity of calcium hydroxide. (Clark’s process)
Permanent Hard Water
» It contains sulphates and chlorides of calcium and magnesium.
» It is converted into soft water by adding sodium carbonate (Na2C03) or calgon or zeolite.
Pollutants
These are the substance that contaminate the environment and of two types
Primary Pollutants
These persist in the environment in the form, they are formed example sulphur dioxide (S02), nitrogen dioxide (N02) etc.
Secondary Pollutants
These are the products of reaction of primary pollutants e.g., PAN, ozone (03), aldehyde etc.
Green House Effect
It is the heating of Earth and its objects because of the trapping of IR radiations by carbon dioxide (C02), methane (CH4), NO, ozone (03), chloro-fluorocarbons and water vapours.
Global Warming
» It is a result of increased concentration of green house gases.
» It may result in melting of ice caps and glaciers, spreading of several infectious diseases like malaria, sleeping sickness etc.
Acid Rain (By Robert Augus)
» It has pH less than 5. It is due to oxides of nitrogen and sulphur.
» It damages the buildings and other structures made up of limestone as marble, corrodes metal pipes, results in several diseases.
» pH of normal rain water is 5.6.
Man Made Materials
Soaps
These are sodium and potassium salts of higher fatty acids, e.g., sodium palmitate, sodium stearate etc.
Detergents
» These are sodium or potassium salts of long chain alkyl or aryl sulphonates or sulphates e.g., sodium alkyl sulphonate, sodium alkyl benzene sulphonate, etc.
» These are also called soapless soap.
* Detergents lather with hard water.
* Detergents cause pollution but straight chain alkyl group containing I detergents are biodegradable and do not cause pollution.
Fertilizers
» These substances increase the fertility of soil by providing elements essential for the growth of plants like nitrogen, phosphorus and potassium, e.g., basic calcium nitrate[CaO.Ca(NO3)2] ammonium sulphate[(NH4)22SO4] . These two increases the acidity of soil. Which is removed by adding lime.
» Other examples are calcium cyanamide or nitrolim (CaCN2), Urea or carbamide (it does not effect the pH of soil), calcium super phosphate or super phosphate of lime[Ca(H2P04)2 +2CaS04 . 2H20]
Glass
» It is an amorphous or transparent solid, also called supercooled liquid.
» It contain mairly silica (Si02).
» Different Substance give Different Colour to Glass
Cement or Portland Cement
» It is a complex material containing the silicates and aluminates of calcium with small amount of gypsum.
» It has the following composition calcium oxide (CaO)= 50-60%, silica (Si02)= 20-25%, alumina (Al203) = 5 -10%; magnesium oxide (MgO) =2-3%.
» It is manufactured from limestone and clay.
» Cement if contains excess lime, cracks during settings arid if lime is less, cement is of weak strength.
» Gypsum decreases the rate of setting of cement.
Medicines
» These are the chemicals used for treating diseases and reducing suffering from pain.
These are classified as
» Analgesics are used to reduce pain, e.g., aspirin, paracetamol, morphine etc.
» Antipyretics is used to reduce body temperature during high fever, e. g., paracetamol, aspirin, phenacetin, analgin, novalgin.
» Tranquilizers are used to treat stress, mild and severe mental disease. These are also called psychotherapeutic drugs, e.g., equanil, valium, veronal, serotonin, chlorodiazepoxide, meprobamate etc.
» Antiseptic prevent the growth of microorganisms or kill them but are not harmful to living tissues. e.g., dettol savlon, iodine tincture, boric acid, hydrogen peroxide etc.
» Antibiotics are obtained from microorganisms and used to destroy the other microorganisms e. g., penicillin, ampicillin, amoxycillin (all are narrow spectrum), ofloxacin, tetracycline, chloramplinol (all are broad spectrum). Penicillin was discovered A. Fleming in 1929.
» Antimalarial are used to treat malaria, e.g., chloroquin.
» Sulpha drugs are alternatives of antibiotics, e.g., sulphanilami.de, sulphadiazine etc.
» Antacids are used as a remedy for acidity, e.g, magnesium hydroxide, sodium bicarbonate (baking soda) etc.
» Pesticides are used to destroy the organisms that harm the crop.
» These are of the following types
1. Insecticides e.g., DDT, aluminium phosphate, gammexane.
2. Fungicide e.g, bordeux mixture.
3. Herbicides e.g, benzipam, benzadox.
4. Rodenticides eg., aluminium phosphide.
Plastics
» These are cross-liked polymers (a substance having high molecular weight and repeating unit) and are very tough.
Lac is a natural plastic (polymer).
Polymers are made up of monomers.
These are of two types.
1. Thermoplastics are the polymers which can be easily softens on heating e.g., polythene, polystyrene, polyvinyl chloride, teflon etc.
2. Thermosetting plastics are the polymers which undergo permanent change on heating due to excessive cross-linking. These cannot be reused, e. g., bakelite.
Biology
» Biology is a natural science concerned with the study of life and living organisms, i.e., plants and animals.
» Study of plants is called Botany and study of animals is called Zoology. Zoology and Botany are collectively called Biology. The term ‘Biology’ was coined by Lamarck and Treviranus.
» The scientist who gave his thought for the first time about the life of plants and animals was Aristotle. That’s why he is known as the Father of Biology. He is also known as the Father of Zoology.
» Theophrastus is known as Father of Botany.
The Cell
» The Cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life and is often called the building block of life.
» The branch of Biology which deals with the study of cell, is called Cytology.
» Robert Hooke coined the term cell when he saw honey comb-like structure in the section of cork. However, he only discovered cell wall.
» The first living cell was discovered by Leeuwenhoek.
* The largest known cells are unfertilized ostrich egg cells (size 6 inch diameter).
* The smallest cell is of PPLO (Mycoplasma gallisepticum-size 1 (0.1-0.3 m).
* Human nerve cell is the longest animal cell.
* Largest a cellular plant Acetabularia is 10 cm and animal Amoeba, is 1 mm
* The largest human cell is the female ovum and the smallest human cell is the red blood cell.
Types of Cells
These are two types
(i) Prokaryotic Cells These are primitive cell, lacking a nucleus and most of the other cell organelles, e.g., bacteria cell.
(ii) Eukaryotic Cells These have nucleus and membrane bound cell organelles. These are present in unicellular and multicellular plant and animal cells.
Deoxyribonucleic Acid (DNA)
» It is a long polymer made from repeating units called nucleotides.
» Each nucleotide consists of a nucleoside (i.e., nitrogenous base and deoxyribose sugar) and a phosphate group, joined together by ester bonds.
» It has four bases, i.e., adenine, guanine, cytosine and thymine.
» Adenine and guanine are the purine bases; cytosine and thymine are pyrimidine bases.
( DNA was discovered by James D Watson and Francis Crick, who got Nobel Prize for this discovery.
Ribonucleic Acid (RNA)
» It is also made up of a long chain of nucleotides.
» Each nucleotide consists of a nitrogenous base, a ribose sugar and a phosphate group.
» It contains uracil in place of thymine.
» RNA is of three types
mRNA (messenger RNA)
rRNA (ribosomal RNA)
LRNA (transfer RNA)
» These three take part in protein synthesis.
Biomolecules
Biomolecules are the substances that are essential for a living being to perform the basic function, e.g., carbohydrate, proteins, lipids (fats), nucleic acids, vitamins, minerals and water.
Carbohydrate
» These are the source of energy and about 50-75% energy is obtained by the oxidation of carbohydrates.
» The main end product of carbohydrate digestion is glucose, which is called blood sugar.
» 1 gm glucose provides about 17 kJ energy or 4.2 kcal energy.
» Carbohydrates are better fuel as compared to proteins and fats as they readily decompose to give energy.
» Main sources of carbohydrates are wheat, maize, rice, potato, etc.
» Excessive intake of carbohydrate results in digestive problems and obesity.
Proteins
» Proteins are polymers of amino acids.
» These are found- in all living cells. These are the compounds of carbon (C), hydrogen (H), oxygen (O), nitrogen (N) and sulphur (S). These form 15% part of human body.
» Their main sources are ground nuts, soyabean, pulses, fish, etc.
» Deficiency of protein caused kwashiorkor and marasmus.
Lipids (Fats)
» These are also the compounds of carbon (C), hydrogen (H) and oxygen (0).
»» Chemically, these are the ester of glycerol and fatty acids.
» These are present in cytoplasm, wall, etc.
» The main sources of fats are ghee, butter, almond, cheese, egg yolk, meat, soyabean, etc.
» Fats are digested, by an enzyme called lipase, in the small intestine.
» These remain under the skin and prevents the loss of heat from the body.
» These protects different body parts from injury.
» Deficiency of fat results in dry skin and weightlessness.
» If fat is in excess, the body gets fatty and result in several heart diseases and high blood pressure.
Roughage
» Roughage is another term for dietary fibre, e.g., Natural food, dalia etc.
» It does not provide energy but only helps in retaining water in the body.
Vitamin
» It was first invented by FG Hopkins. However, the term vitamin was coined by C Funk.
» Vitamin is an organic compound, which cannot be synthesized in sufficient quantities by an organism and must be obtained from the diet.
» It provide no calories, they only regulate chemical reactions occuring in the metabolism of the body.
» These are divided into two groups
(i) Fat soluble vitamin, viz., Vitamin-A, D, E and K.
(ii) Water soluble vitamin, viz., Vitamin-B group and C.
» Vitamin-B 12 contains cobalt.
» Vitamin-D is synthesized in our skin by the action of ultraviolet rays of the sunlight.
» Vitamin-K is synthesized in our colon by the bacteria.
Mineral Nutrients
» These are metals non-metals and their salts other than the four elements- carbon, hydrogen, nitrogen, oxygen and constitute about 4% of total body weight.
Origin of Life
» The first scientific account of the origin of life was given by Russian scientist AI Oparin in his book origin of life.
» More and more creation of organism by gradual charges from low categories animal higher animal is called organic evolution.
» Jean-Baptiste de Lamarck give the idea that an organism can pass on characteristics) that it acquired during its life time to its offspring (also known as her itability of acquired characteristics).
» Darwin’s theory of evolution was Origin of Species by Natural Selection and it was published in 1895.
Classification of Organisms
In Linnaeus time, a two kingdom system of classification with Plantae and Animalia kingdoms was developed. The system did not distinguish between the eukaryotes and prokaryotes, unicellular and multicellular and photosynthetic organisms.
PH Whittaker (1969) proposed a five kingdom classification. The kingdom named were Monera, Protista, Fungi, Plantae and Animalia.
Genetics
it is the study of heredity and variations. The term ‘Genetics’ was coined by W Bateson in 1905. Gregor Johnn Mendel (Commonly called Father of Genetics) proposed three laws.
(a) Law of dominance
(b) Law of segregation
(c) Law of Independent Assortments
» The 7 characters studies by Mendel were present as four different chromosomes. To know hetero geneity of F1 be crossed F1 hybrid with recessive parent, this is called test cross.
» Haemophilia and colourblindness are two important sex-linked diseases in human, whose allele is found on x-chromosome.
Human Body
The human skin (integumentary) is composed of a minimum of three major layers of tissue, the epidermis, the dermis and hypodermis.
Epidermis
The top layer of skin made up of epithelial cells and does not contain blood vessels.
Dermis
» It gives elasticity to the integument, allowing stretching and conferring flexibility, while also resisting distortions, wrinkling and sagging.
Hypodermis
» It is made up of adipose tissue.
» It performs several important functions
(i) Protect against invasion by infectious organisms.
(ii) Act as a receptor for touch, pressure, pain, heat and cold.
(iii) Protect the body against sunburns by secreting melanin.
(iv) Generate vitamin-D through exposure to ultraviolet light.
(v) Store water, fat, glucose and vitamin-D.
Digestive System
» The human digestive system consists of alimentary canal and digestive glands. The alimentary canal consists of mouth (having teeth and tongue Oesophagus, stomach, small intestine and large intestine.
» Ingestion takes place in buccal cavity.
» Saliva lubricates the food and binds the food particles together to form bolus.
» Salivary gland have starch spitting enzyme ptyalin.
» The food passes down through the oesophagus into stomach.
» Now food is mixed with gastic juice and hydrochloric acid which disinfect the food and creates acidic medium.
» Pepsin digests proteins and converts them into peptones.
» Renin convert milk to curd.
» Digested food now is called chyme and moves to duodenum.
» Food is mixed with bile (liver) to breakdown fats into smaller globules.
» Trypsin acts upon proteins and breaks them into polypeptides.
» Amylase converts starch into simple sugar.
» Lypase converts fats into fatty acids and glycerol.
» Food passes into ileum and mixes with intestinal juice (alkaline in nature) where
» Maltase converts maltose into glucose
» Lactase converts lactose into glucose and galactose
» Sucrase converts sucrose into glucose and fructose
» Trypsin digests the peptides into amino acids
» Food now is called chyle and moves to Ileum.
» Ileum’s internal surface has finger-like folds called villi.
» It helps in absorption of food.
Respiratory System
Respiration is a catabolic process in which the respired oxygen is used in the oxidation of food resulting in the release of energy. It is brought about by respiratory organs.
Aerobic Respiration
» The respiration takes place in the presence of oxygen is known as aerobic respiration.
» This oxygen oxidized the respiratory substance into carbon dioxide, water and energy.
Anaerobic Respiration
» The respiration takes place in the absence of oxygen is known as anaerobic respiration.
» It is found in endoparasites like roundworm.
» In this process, the respiratory substances are incompletely oxidized to carbon dioxide and alcohol.
Human Respiratory System
» Overall passage of air in humans is as follows Nostrils Pharynx -> Larynx Trachea -> Bronchi -> Bronchioles -> Alveoli -> Cells -> Blood.
» In humans respiration takes place in two phases
External Respiration (Breathing or Ventilation of Lungs)
» It involves inspiration and expiration of air.
» Inspiration is the process of intake of air. During inspiration, muscle of the diaphragm contract and diaphragm flatten.
» Expiration is breathing out of air. During expiration, relaxation of muscles of the ribs and diaphragm takes place. Diaphragm again become dome-shaped. Chest cavity is reduced and air is forced outward through nose and trachea.
» Breathing rate in human is 18 – 20/min.
Internal Respiration (Oxidation of Food)
» It is a complex process in which food is broken down to release energy. It is a biochemical phase takes place inside the cell.
» Transportation of oxygen takes place by haemoglobin of blood. Whereas transportation of only 10-20% cdrbon dioxide takes place by haemoglobin of blood.
Heart
» Heart is a thick, muscular, contractile, automatic pumping organ of blood vascular system.
» The chamber which receives the blood from body tissues are called auricles and the chambers of heart which pump blood to body tissues are called ventricles.
» There is a thin two layered sac around the heart known as pericardium, filled with a watery fluid called pericardial fluid, which allows frictionless movements of heart and protects it from mechanical shocks.
» A fish has only two-chambered heart (one auricle and one ventricle).
» In amphibians, heart is three-chambered.
» In crocodile, birds and mammals the heart is divided into four chambers (two auricles and two ventricles).
Reptilian heart is structurally three-chambered but is functionally four-chambered (i.e., incomplete four- chambered) except in crocodile.
» A new born baby’s heart weight about 20 g.
» The average weight of heart in men is 280-340 g, while in women is 230-280 g.
» To pump out blood, the heart chamber undergo alternate contration called systole and relaxation called diastole. The regular sequence of these systole and diastole causes the heart sound Lub and Dub.
» Arteries carry pure blood from the heart while veins carry impure blood to the heart.
» Human heart beat is myogenic in nature, i. e., initiated by a patch of modified heart muscles itself without requiring an external stimulation. This patch is called SA node (sino-auricular node) or pacemaker.
Blood
» Blood is fluid connective tissue and composed of blood corpuscles, plasma and platelets.
» It is slightly alkaline is nature (pH 7.4).
» Its volume in an adult in 5.8 L
» The oxygenated or pure blood is bright red while the deoxygenated blood in purple coloured (Darker shade of red).
» During blood clotting fibrinogen changes into fibrin by thrombin which is obtained from thromboplastin in the presence of Ca2+.
» The haemoglobin contents of adult female amount from 13.5 to 14.5% whereas in adult male its amount from 14.5 to 15.5%
Plasma
» About 55% of whole blood is blood plasma, the blood’s liquid medium, and is straw-yellow in colour.
» It contains 92% water, 8% blood plasma proteins and trace amounts of other materials.
Human Skeleton
» The total number of bones in adult human is 206.
» Femur is longest bone and stapes is smallest bone.
» Fibula is thinnest bone.
» The muscles which join bone to bone are called ligaments.
Excretory System
» The process of removal of nitrogenous wastes from the body is called excretion. The organs of excretion are called excretory organs.
Human Excretory System
» The human urinary system includes-the kidneys (two), ureters (two), urinary bladder (one) and urethra (one). It is bean-shaped, chocolate brown structure lying in the abdomen, one on each side of the vertebral column just below the diaphragm.
» These form the urine and controls osmotic pressure within the organism with respect lo external environment. Nephrons are the functional and structural unit of kidney. They contain Bowmann’s capsule and Henle’s loop.
Brain
» Brain lies in the cranium of skull.
» Cerebrospinal fluid is present in and around brain and spinal cord.
(i) Cerebrum leads to consciousness, storage of memory of information.
(ii) Thalamus deals with pain, pressure and temperature.
(iii) Hypothalamus deals with water balance is body, behavioural patterns of sex, sleep, stress emotions, etc. It also regulates pituitary hormones and metabolism of fat, carbohydrate and water.
(vi) Midbrain deals with visual analysis, auditory, etc.
(v) Cerebellum controlls coordination of accurate movements and balancing.
(vi) Medulla oblongata is long connecting part of brain to spinal cord. It deals with control of heart beats, blood vessels, breathing, salivary secretion and most of reflex and involuntary (uncontrolled) movements.
Spinal Cord
» Deals with impulses to and from the brain and is the centre for reflex actions like blinking of the eye when an object comes near to our eyes suddenly, Rapid withdrawal of hand while burned, knee jerk reflex, etc.
Practice Exercise
1. Which of the following is used as a coolant in nuclear reactors?
(a) Heavy water
(b) Cadmium
(c) Liquid sodium
(d) Graphite
2. Which of the following has the least penetrating power?
(a) Alpha particles
(b) Beta particles
(c) Gamma rays
(d) All have the same penetrating power
3. Optic fibres are mainly used for which of the following?
(a) Communication
(b) Weaving
(c) Musical instruments
(d) Food industry
4. Which of the following are most penetrating?
(a) α-rays
(b) β -rays
(c) γ-rays
(d) X-rays
5. Old-written material, which cannot be read easily, can be read by
(a) cosmic rays
(b) ultraviolet rays
(c) infrared rays
(d) None of these
6. Cryogenic engines find applications in
(a) rocket technology
(b) frost-free refrigerators
(c) sub-marine propulsion
(d) researches in superconductivity
7. Which of the following take place when the subject speaks untruth while being tested by the polygraph instrument?
1. His blood pressure goes up.
2. His pulse quickens.
3. His skin darkens.
4. He sneezes.
(a) 1 and 2
(b) 3 and 4
(c) 1,2 and 3
(d) 2,1 and 3
8. The best colour(s) for a sun umbrella will be
(a) black
(b) black on top and white on the inside
(c) white on top and black on the inside
(d) printed with all the seven colours of rainbow
9. Which of the following laws is explained by the statement that matter can neither be created for destroyed?
(a) Law of Conservation of Energy
(b) Le Chatelier’s principle
(c) Law of Conservation of Mass
(d) Law of Osmosis
10. Aviation fuel for jet aeroplanes consists of purified
(a) petrol
(b) kerosene
(c) gasoline
(d) diesel
11. Which of the following is the correct combination of the inventors and the inventions?
(a) Galileo Galilei – Transistors
(b) Elisha Thomson -Windmill
(c) JL Baird – Television
(d) Sir Frank Whittle – Laser
12. Who among the following laid the foundation of nuclear science in the country?
(a) Vikram Sarabhai
(b) Homi j Bhabha
(c) MGK Menon
(d) Raja Ramanna
13. A bomb is dropped at a point from a moving aeroplane. The pilot observes that
(a) the bomb traverses a curved path and falls some distance behind that point
(b) the bomb traverses a curved path and falls some distance ahead
(c) the bomb drops vertically downward
(d) the bomb remains stationary in the air for some time
14. Rise of mercury in a barometer indicates
(a) fair weather
(b) storm
(c) rain
(d) (b) and (c)
15. The source of our energy is basically the
(a) ocean
(b) sun
(c) atmosphere
(d) space
16. When light passes from air into glass it experiences change in
(a) frequency and wavelength
(b) frequency and speed
(c) wavelength and speed
(d) frequency, wavelength and speed
17.Which of the following are the discoveries of Einstein?
(a) Radioactivity and photoelectric effect
(b) Radioactivity and theory of relativity
(c) Theory of relativity and photoelectric effect
(d) X-rays and photoelectric effect
18. A convex mirror makes a good rear-view mirror for a car because
(a) it does not form diminished images
(b) it has no focal point
(c) its images can be thrown on a screen
(d) it forms erect, reduced images
19. The nuclides having the same number of neutrons but different number of protons or mass number are known as
(a) isobars
(b) isoelectronic
(c) isotopes
(d) isotones
20. Why is there a spluttering sound when water is sprinkled on hot oil?
(a) Boiling point of the water is higher than that of oil
(b) Boiling point of the oil is higher than that of water
(c) Oil and water do not mix
(d) Oil and water combine to form a compound
21. Which falls down faster in a vacuum-a feather, a wooden ball or a steel ball ?
(a) A wooden ball
(b) A feather
(c) A steel ball
(d) All will fall down at the same speed in a vacuum because there will be no air resistance
22. Materials used for making cooking utensils should have
(a) low specific heat and high thermal conductivity
(b) high specific heat and high thermal conductivity
(c) low specific heat and low thermal conductivity
(d) high specific heat and low thermal conductivity
23. Transfer of heat energy from the sun to the moon takes place by
(a) radiation only
(b) radiation and conduction
(c) radiation and convection
(d) radiation, conduction and convection
24. Match the following
25. Microphone is a device in which
(a) sound waves are directly transmitted
(b) electrical energy is converted into sound waves directly
(c) sound waves are converted into electrical energy and then reconverted into sound after transmission
(d) amplification is not required at all
26. The blue colour of the water in the sea is due to
(a) absorption of other colours by water molecules
(b) reflection of the blue light by the impurities in sea water
(c) reflection of blue sky by sea water and scattering of blue fight by water molecules
(d) None of the above
27. A lighted candle gets extinguished when covered with a tumbler because of
(a) adequate supply of air
(b) inadequate supply of air
(c) presence of non-luminous matter
(d) None of the above
28. Consider the following statements
The fog during winter season is more on the day when
1. sky is clear
2. sky is cloudy
3. wind is blowing
Which of the statements given above is/are correct?
(a) Only 1
(b) 1 and 3
(c) 2 and 3
(d) Only 2
29. Which of the following is good nuclear fuel?
(a) Uranium-238
(b) Neptunium-239
(c) Thorium-236
(d) Plutonium-239
30. In an atomic explosion, enormous energy is released which is due to the
(a) conversion of neutrons into protons
(b) conversion of chemical energy into heat energy
(c) conversion of chemical energy into nuclear energy
(d) conversion of mass into energy
31. Kinetic energy depends
(a) on the mass of the moving body
(b) the velocity or speed of the moving body
(c) the pressure of the moving body
(d) both mass and velocity of the moving body
32. Oil rises up the wick in a lamp because
(a) oil is very fight
(b) of the diffusion of oil through the wick
(c) of the surface tension phenomenon
(d) of tire capillary action phenomenon
33. The most abundant metal in the earth’s crust is
(a) zinc
(b) copper
(c) aluminium
(d) iron
34. An alloy used in making heating elements for electric heating devices is
(a) solder
(b) alloy steel
(c) nichrome
(d) German silver
35. The filament of an electric bulb is made of
(a) iron
(b) nichrome
(c) tungsten
(d) graphite
36. Carbon, diamond and graphite are together called
(a) isomers
(b) allotropes
(c) isomorphs
(d) isotopes
37. Galvanised iron sheets have a coating of
(a) tin
(b) lead
(c) zinc
(d) chromium
38. Which of the following metals was first discovered by man?
(a) Bronze
(b) Silver
(c) Iron
(d) Copper
39. An element that does not occur in nature but can be produced artificially is
(a) thorium
(b) radium
(c) plutonium
(d) uranium
40. The element found on the surface of the moon is
(a) tin
(b) tungsten
(c) tantalum
(d) titanium
41. The average salinity of sea water is
(a) 20%
(b) 25%
(c) 30%
(d) 35%
42. The metallic constituents of hard water are
(a) magnesium, calcium and tin
(b) iron, tin and calcium
(c) calcium, magnesium and iron
(d) magnesium, tin and iron
43. The high-temperature superconductors are
(a) metal alloys
(b) ceramic oxides
(c) inorganic polymers
(d) pure rare earth metals
44. The variety of coal in which the deposit contains recognizable traces of the original plant material is
(a) anthracite
(b) lignite
(c) peat
(d) bitumen
45. The highest grade of coal whose surface is shining and has the highest calorific value, is
(a) Bituminous
(b) Lignite
(c) Anthracite
(d) Peat
46. An atom of an element with mass number 23 and atomic number 11 will have
(a) 11 neutrons, 12 protons and 11 electrons
(b) 11 protons, 12 neutrons and 11 electrons
(c) 11 neutrons, 11 protons and 12 electrons
(d) 23 protons and 11 electrons
47. What are soaps?
(a) Salts of silicates
(b) Esters of heavy fatty acids
(c) Sodium or potassium salts of heavier fatty acids
(d) Mixture of glycerol and alcohols
48. In vulcanization, natural rubber is heated with
(a) Carbon
(b) Sulphur
(c) Silicon
(d) Phosphorus
49. Which of the following is used as a filler in rubber tyres?
(a) Graphite
(b) Coal
(c) Coke
(d) Carbon black
50. Which of the following is used in beauty parlours for hair setting?
(a) Chlorine
(b) Sulphur
(c) Phosphorus
(d) Silicon
51. Which of the following is the lightest gas?
(a) Nitrogen
(b) Hydrogen
(c) Ammonia
(d) Carbon dioxide
52. Match the following
53. Among the various allotropes of carbon
(a) diamond is the hardest, lamp black is the softest
(b) diamond is the hardest, coke is the softest
(c) coke is the hardest, graphite is the softest
(d) diamond is the hardest, graphite is the softest
54. Which one of the following is the basis of modern periodic table?
(a) Atomic mass
(b) Atomic number
(c) Atomic size
(d) Atomic volume
55. Match the following
56.Which is/are the important raw material(s) required in cement industry?
(a) Limestone
(b) Gypsum and clay
(c) Clay
(d) Limestone and clay
57. Glass is made of the mixture of
(a) quartz and mica
(b) sand and salt
(c) sand and silicates
(d) None of these
58. Which one of the following metals has the highest density?
(a) Gold
(b) Iron
(c) Platinum
(d) Lead
59. The quantum theory was first enunciated by
(a) Niel Bohr
(b) Albert Einstein
(c) Max Planck
(d) Max Bom
60. The noble gases do not react with any other atom because
(a) they are heavy elements
(b) they are stable compounds
(c) their outermost orbits contain eight electrons
(d) None of the above
61.Which of the following are true about kwashiorkar disease?
1. It occurs in infants upto 1 year of age.
2. It is characterised by oedema ie. swelling of the body.
3. The skin of the person suffering from it becomes dry and hair turns reddish.
4. It can be cured by giving a protein-rich diet.
(a) 1,2 and 3
(b) 2, 3 and 4
(c) 1,3 and 4
(d) 1, 2 and 4
62.What is the importance of roughage in our diet?
1. It helps in retaining water in the body.
2. It is necessary for normal functioning of the liver.
3. It adds bulk to the food and prevents constipation.
(a) 1 and 2
(b) 2 and 3
(c) 1 and 3
(d) Only 3
63.Which of the following vitamins is synthesised in the body by intestinal bacteria?
(a) Vitamin B1
(b) Vitamin B4
(c) Vitamin D
(d) Vitamin K
64.Which acid is produced when milk gets sour?
(a) Acetic acid
(b) Tartaric acid
(c) Lactic acid
(d) Butyric acid
65.Which of the following synthesised by our body?
1. Vitamin B6
2. Vitamin D
3. Vitamin E
4. Vitamin K
(a) 1 and 2
(b) 2 and 3
(c) 2 and 4
(d) 1 and 4
66.The most important requirement for the people of a flood hit area is
(a) small pox vaccination
(b) BCG injection
(c) inoculation against cholera
(d) None of the above
67.Sugar syrup is used for the preservation of fruits because it
(a) kills the microorganisms present in them
(b) helps to improve their taste and flavour
(c) drains moisture to inhibit growth of microorganisms
(d) mixes well with the fruits
68.Bionics is the science of
1. application of mathematics to the study of living things
2. application of the knowledge of the living world characteristics to the world of machines
3. study of relation of an organism to its environment
4. study of laws of life
(a) 1 and 2
(b) Only 2
(c) Only 3
(d) 1 and 4.
69. Salt is used in our food because
(a) it makes the food tasty
(b) we sweat and lose salt
(c) it helps in production of hydrochloric acid required to digest the food
(d) it makes water absorb food particles better
70. The vitamin which is generally excreted by humans in urine is
(a) vitamin A
(b) vitamin D
(c) vitamin C
(d) None of these
71. A person who lives exclusively on milk, egg and bread is likey to become a victim of
(a) rickets
(b) scurvy
(c) xerophthalmia
(d) None of these
72. A girl ate sweets while fanning the flies away. Due to this, she suffered from a disease diagnosed as
(a) kwashiorkar
(b) tuberculosis
(c) diphtheria
(d) cholera
73. Calcium content is maximum in
(a) bajra
(b) maize
(c) sorghum
(d) wheat
74. Which of the following has been found useful in keeping cholesterol level down?
(a) Tulsi
(b) Turmeric
(c) Garlic
(d) Serpentina
75. Ready source of energy available for athletes is
(a) carbohydrates
(b) fats
(c) proteins
(d) vitamins
76. Milk, cheese and eggs are the source of vitamins?
(a) B and C
(b) A and C
(c) C and D
(d) A and D
77. For pasteurisation of milk by Flash method, milk is heated to a temperature of
(a) 10°C
(b) 37°C
(c) 72°C
(d) 100°C
78. Transfer of genetic information from one generation to the other is accomplished by
(a) DNA
(b) messenger RNA
(c) transfer RNA
(d) Both (b) and (c)
79. The unit structure of which gene is made up of is
(a) RNA
(b) nucleotides
(c) DNA
(d) endoplasmic reticulum
80. Rigidity of cell wall is due to
(a) chitin
(b) lignin
(c) suberin
(d) pectin
81. Cell theory was propounded by
(a) R Virchow
(b) Robert Hooke
(c) Schleiden and Schwann
(d) William Harvey
82. Which of the following are the pollutants that a traffic constable is likely to inhale?
1. Carbon monoxide
2. Lead
3. Sulphur dioxide
4. Oxides of nitrogen
(a) 1,2 and 3
(b) 1,2 and 4
(c) 1,3 and 4
(d) 2, 3 and 4
83. The yellow colour of urine is due to the presence of
(a) bile
(b) lymph
(c) cholestrol
(d) urochrome
84. There are approximately …… muscles in human body.
(a) 200
(b) 350
(c) 500
(d) 700
85. The pitch of the voice of women is generally
(a) same as that of men
(b) higher than that of men
(c) much lower than that of men
(d) None of the above
86. Biological death of a patient means death of tissues of the
(a) kidney
(b) heart
(c) lungs
(d) brain
87. Which of the following hormones contains iodine?
(a) Adrenaline
(b) Insulin
(c) Testosterone
(d) Thyroxine
88. Respiratory centre is situated in
(a) cerebrum
(b) cerebellum,
(c) medulla oblongata
(d) diencephalon
89. The pH of human blood is between
(a) 6.5-7
(b) 7.5 – 8
(c) 8-9
(d) 4.5-5
90. For transfusion, the ‘O’ blood group of a donor can be accepted by a person having blood group
(a) A
(b) B
(c) AB
(d) All of these
91. The largest gland in the human body is
(a) heart
(b) liver
(c) kidney
(d) brain
92. In which organ of the human body are the lymphocyte cells formed?
(a) Liver
(b) Long bone
(c) Pancreas
(d) Spleen
93. The Hepatitis-B, which affects liver, is actually a
(a) Virus
(b) Bacterium
(c) Protozoan
(d) Helminth
94. The short upper part of the human intestine next to the stomach is called
(a) Caecum
(b) Duodenum
(c) Ileum
(d) Jejunum
95. Desert plants would be characterised by
(a) vivipary
(b) aerenchyma
(c) aerial roots
(d) sunken stomata
96. Flower colours are due to
(a) chlorophyll
(b) melanin
(c) phytochromes
(d) anthocyanins
97. The sweetest sugar is
(a) Sucrose
(b) glucose
(c) fructose
(d) lactose
98. Which of the following is a skin disease?
(a) Anaemia
(b) Pellagra
(c) Osteomalacia
(d) Rickets
99. Which of the following vitamins is essential for bone and teeth formation?
(a) Vitamin A
(b) Vitamin B
(c) Vitamin C
(d) Vitamin D
100. Healing of wounds is hastened by vitamin
(a) A
(b) C
(c) E
(d) K
Answer
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