Chapter 1:- Crop production and management
1. Agricultural practice:-Various tasks performed by farmers for crop production are termed as Agricultural practices
2. Animal husbandry:-. Animals reared at home or in farms have to be provided with proper food, shelter and care. When this is done on a large scale, it is called animal husbandry.
3. Crop:-Crop is a plant that is grown on a large scale commercially.
Pulses, Cereals, Oil seeds, Vegetables & fruits are different types of crop.
4. Fertiliser:-Fertilizers are commercially produced plant nutrients. They result in higher yields & healthy plants, if applied in proper dose
5. Granaries:- Storehouse where large scale storage of grains is done to protect them from pests like rats and insects.
6. Harvesting:-Harvesting is cutting of crop after it is matured. The season of harvesting brings a lot of happiness as this is time when the hard work of farmers brings results.
7. Irrigation:-Irrigation is artificial application of water to soil to ensure growth of agricultural crops.
8. Kharif:-Crops grown in rainy season are termed as Kharif crops. Examples: Maize, soyabean, sugarcane
9. Manure:-Manure is an organic substance that increases soil fertility. It is prepared from decomposition of animal excreta & plant wastes.
10. Plough:-Tool used for ploughing . It is made of iron/ wood. It is pulled by a pair of animals like cows/ oxen/ horses and operated by the farmer through the handle
11. Rabi :-Crops grown in winter season are termed as Rabi crops. Examples: Wheat, Gram, Pea
12. Seeds:- the small hard part of a plant from which a new plant of the same kind can grow.
13. Silo:- Towers where large scale storage of grains is done to protect them from pests like rats and insects.
14. Sowing:-Scattering seeds on the Earth after soil is prepared for cultivation is termed as Sowing
15. Storage:- Proper storage of food grains is important to protect against moisture, micro-organisms & insects.
16. Threshing:- In the harvested crop, the grain seeds need to be separated from the chaff. This process is called threshing. This is carried out with the help of a machine called combine which is a harvester as well as a thresher.
17. Weeds:-Weeds are unwanted plants in the cultivated field. They compete for nutrients, space, water & light, therefore, adversely affect crop growth.
18. Weedicides:-These are chemicals which kill weeds without damaging the crops.
19. Winnowing:-Threshing can be done manually using a process called ‘Winnowing’
In this process, grains are separated from chaff by throwing into the air. Chaff gets carried away by wind, while grains fall back.
Chapter :- 2 Micro-organisms friend and foe
1. Algae:- these are multicellular,aquatic microorganisms Example:-Spirogyra, Ulothrix, Chlamydomonas
2. Antibiotics:-Antibiotics are chemical substances that kill disease-causing microbes
3.Antibodies:- Proteins which are produce by our body to fight the invader.
4.Bacteria :- Bacteria are one of the oldest unicellular life form that appear appear in a variety of shapes & sizes (Spherical, elongated, spiral etc.)
5.Carrier:- Agents which carry pathogens to healthy person. Ex :- female anopheles mosquito , female Aedes
6. Communicable diseases:- Microbial diseases that can spread from an infected person to a healthy person through air, water, food or physical contact are called communicable disease . Ex cholera, common cold, chicken pox and tuberculosis.
7. Fermentation:- The process of conversion of sugar into alcohol is called fermentation.
8. Fungi:-Fungi are multicellular, Heterotrophic, immobile life form that found in moist and humid climate.
9. Lactobacillus:-Curd contains a bacterium, Lactobacillus
It is a friendly-bacterium
10. Micro-organisms:- organism which are too small to see with naked eyes. They can be seen with microscope or magnifying glass.
11. Nitrogen cycle:- Nitrogen cycle is all about the movement of nitrogen between various elements on Earth
12. Nitrogen fixation:- The process of fixing atmospheric nitrogen into soil by nitrogen fixers is called nitrogen fixation.
13. Pasteurization is a technique that makes use of heat & cold treatments to preserve food items. In this process, milk is heated to about 700C for 15-30 sec & then suddenly chilled & stored. This technique was invented by Louis Pasteur (1864).
14 Pathogen: disease-causing organisms are called Pathogens. Pathogens include bacteria, viruses, fungi & protozoa.
15. Preservation:- The process of protecting food from the attack of microorganisms is called preservation
16. Protozoa:- Group of single celled organisms like Amoeba, Paramecium etc is called Protozoa
17.Rhizobium:- Nitrogen fixing bacteria which is present in the roots on leguminous plants us called rhizobium
18:- vaccine:-vaccine is a biological preparation that resembles a disease causing microbe. These vaccines are made up of dead or very weak microbes.
19. Virus:-microorganisms which behave like non-living when outside host cell, and reproduce only when inside the host cell
20. Yeast:- A single celled organism which helps in fermentation .
Chap 3 synthetic fibres and plastics
1. Acrylic :-synthetic fibre which is formulated from a polymer called polyacrylonitrile.It is lightweight, soft, warm, and has resemblance with wool.
2. Artificial silk :- The fibre that is obtained by chemical treatment of wood pulp is called artificial silk Or rayon.
3. Nylon:- Synthetic fibre that is prepared from coal, water and air. It is the first fully synthetic fibre.
4. Plastic :- A light , strong and durable polymer that is used to make chairs , slippers, decoration pieces etc.
5. Polyester:- Synthetic fibre that doesn't get wrinkled easily.
6. Polymer :- Many small units combine together to form a large single unit called polymer
7. Polythene :- A type of plastic which is formed by combination of many ethene molecules.
8. Rayon :- The fibre that is obtained by chemical treatment of wood pulp is called artificial silk Or rayon
9. Synthetic fibres :- Man made fibre is called synthetic fibre. Ex:- Nylon , Rayon, polyester and acrylic etc.
10. Terylene :- It is a kind of polyester that can be drawn into very fine fibres that can be woven like any other yarn
11. Thermoplastics :- The plastic which gets deformed easily on heating and can be bent easily are known as thermoplastic
12. Thermosetting plastic :- The plastic which donot gets deformed easily on heating and can be bent easily are known as thermoplastic
Chap 4:- Materials: Metals and Non metals
1. Atom :- The smallest unit of matter which contains electron , proton and neutron as subatomic particles.
2. Conductor :- The substances which allow electricity to pass through it . Example:- metals are good conductors .
3. Displacement reaction :- A reaction in which a more reactive element displace less reactive element from its salt solution. Example:- Iron + Copper sulphate --> Iron sulphate + copper.
4. Ductility :- The ability of metals to be drawn into thin wires is called ductility. Example:- Gold is most ductile metal.
5. Elements :- Pure species which is made up of only one kind of atoms.
6. Hardness :- The ability of a substance to resist cutting and grinding is called hardness. Metals are generally hard. The hardness varies from metal to metal . Except :- lithium, sodium, potassium.
7. Malleability :- Some metals can be beaten into sheets. This property is called malleability. Example:- gold and silver are the most malleable metals
8. Metals :- Substances which are electropositive in nature i.e. they have a tendency to lose electrons. Example:- Sodium, iron, copper, gold, silver, etc.
9. Metalloids :- The elements which have properties in between metals and non metals. Example:- boron, silicon etc.
10. Non metals :- Substances which are electronegative in nature i.e. they have a tendency to gain electrons. Example:- Carbon, Sulphur, Iodine, Oxygen, Hydrogen etc.
11. Sonorous :- Metals produce ringing sounds this property is called sonorous.
Chap 5 :- Coal and Petroleum
1. Coal :- A black coloured hard substance that is composed of carbon, hydrogen, nitrogen, oxygen, minor amount of sulphur.
2. Coal gas :- It is a gaseous mixture of hydrogen, methane, and carbon monoxide
3. Coal tar :- Black, thick and viscous liquid that contains 42% carbon, 48% hydrocarbons and rest of the percentage is occupied by water
4. Coke :- Hard, black coloured and porous derivative of coal.It is a pure form of carbon with less content of impurities and has high carbon content.
5. Fossil fuels:- Fossil fuel refers to the deposits of organic materials, formulated from dead plants and animals under several thousand feet of silt. It's formation takes millions of years
6. Natural gas:- It is a cleaner fuel that is stored under high pressure as compressed natural gas.
7. Petroleum :- It is a clear, green or black coloured oily liquid matter that can be either thin like gasoline or thick like tar.
8. Petroleum refinery :- Process of separation of the wide variety of constituents of petroleum is called Refining of Petroleum carried out in petroleum refinery
Chap 6 :- Combustion and Flame
1. Acid Rain :- Oxides of sulphur and nitrogen dissolve in rain water and form acids . Such a rain is Called acid rain.
2. Calorific value:- Amount of heat energy produced on complete combustion of 1Kg of a fuel is called calorific value. It's unit is KJ/kg
3. Combustion :- A chemical process in which a substance reacts with oxygen to give off heat is called combustion.
4. Deforestation :- Clearing of forests(by cutting down forest trees)over a wide area is called deforestation.
5. Explosion :- The combination which is accompanied by heat, light and sound is called explosion.
6. Flame :- The visible gaseous part of fire which is hot, glowing ignited gas during combustion is called flame.
7. Fire extinguisher :-The job of a fire extinguisher is to cut off the supply of air or bring down the temperature of the fuel.
8. Fuel :- Combustible substance which release enough heat energy to be used for domestic and industrial purposes. Example :- LPG, CNG, Wood, Coal, petroleum etc .
9. Fuel efficiency:- The amount of heat produced by the complete combustion of unit mass of a fuel is known as fuel efficiency.
10. Global warming:- Rise in the temperature of the atmosphere of the earth due to production of acidic oxides during combustion of fuel is called global warming.
11. Ideal fuel :- The fuel which is cheap, easily available, have low ignition temperature ,high calorific value and doesn't produce residue is called ideal fuel.
12. Ignition temperature :- Lowest temperature at which a substance catches fire is called ignition temperature.
13. Inflammable substances The substances which have very low ignition temperature and can easily catch fire with a flame is called inflammable substances.
Chap 7 :- Conservation of Plants and animals
1. Biodiversity:- the existence of a number of different kinds of animals and plants which together make a good and healthy environment
2. Biosphere reserve:- biosphere reserve is a place where animals and some species of plants are kept safely.
3. Deforestation :- This process of removal of a forest or collection of trees from a land and thereafter converting the land to a non-forest use is called deforestation.
4. Desertification :- When a fertile land gets converted to a barren land by deforestation, this is called desertification
5. Ecosystem :- All the interacting organisms in an area together with non-living constituents of the environment forms an ecosystem.E.g. Forests, ponds.
6. Endangered species:- The species of plants and animals whose number is reducing to a level where they may no more exist in nature are called Endangered species
7. Endemic species :- The species of plants and animals that can be found only in a specific region are called Endemic species
8. Extinct :- The species of plants and animals that no more exist in nature due to unsuitable habitat are called Extinct species.
9. Fauna :- The animals of a particular region are called fauna of that region
10. Flora :- The plants of that region are called flora of that region
11. Migratory birds:- Birds that travel from their own habitat to a different habitat due to several reasons at a certain period of the year.
12. National park :- Protected areas intended to provide a natural habitat with all natural resources to the animals where they can freely roam and use the habitat are called national park.
13. Red data book :- The source book that is used to keep a record of endangered species of plants, animals and other species existing within the territory of the state or country is called red data book.
14. Reforestation :- the act of planting new trees in an area or region where they were cut down previously
15. Sanctuary :- a place where birds or animals are protected from being hunted
Chap 8 :- Cell - Structure and Functions
1. Cell:- Cell is the structural and functional unit of life
2. Cell membrane:- Thin , delicate, living and outermost membrane which bound cytoplasm.
3. Cell wall:- Non-living , rigid, outermost covering of plant cell which is fully permeable.
4. Chloroplast:- Green colour plastid which contain chlorophyll.
5. Chromosome:- Rod shaped structure that formed when chromatin condense together when the cell is about to divide
6. Cytoplasm:- Jelly like structure present between the cell membrane and the nucleus.
7. Eukaryotes:- Organisms whose cells have well organised nucleus with a nuclear membrane
8. Gene:-Unit of inheritance in living organisms which control the transfer of a hereditary characteristics from parent to offspring.
9. Multicellular:- organisms made up of more than one cell are called multicellular organisms
10. Nuclear membrane:- Double layered covering of nucleus which separate material inside nucleus from cytoplasm
11. Nucleolus:- Structure embedded in nucleoplasm and compose of proteins and RNA
12. Nucleus:- A structure which is present near centre of eukaryotic cell.
13. Organ:- Group of tissue together make functional unit called organ
14. Organelles:- Membrane bound structure due to which a cell is able to live and perform all its functions
15. Plasma membrane:- Thin, delicate, living outermost covering of cell which ensure protection of cell
16. Plastid :- Organelles present in plant cells only and provide colour and store food to it
17. Prokaryotes:- Organisms whose cells have nuclear material without nucleus membrane
18. Pseudopodia:- False finger like projection which Amoeba possess for intake of food
19. Tissue:- Group of cell which have common origin and perform same function is called tissue
20. Unicellular:- Single celled organism is called unicellular
21. Vacuole:- Organelles which store food and is surrounded by tonoplast
22. White blood cell (WBC) :- Blood cells which fight against germs
Chap 9 :- Reproduction in animals
1. Asexual reproduction:- The type of reproduction in which only a single parent is involved is called asexual reproduction
2. Binary fission:- A mode of asexual reproduction in which an organism reproduce by dividing itself into two is called binary fission. Ex:- Amoeba
3. Budding:- A mode of asexual reproduction in which new individuals develop from buds is called budding. Example:- Hydra
4. Eggs:- the ovary produces female gamete called egg or ovum
5. Embryo :- The zygote divide and redivide to form groups of cells that develop into different tissues and organs of the body. This developing structure is termed as an embryo.
6. External fertilization:- Fertilization that takes place outside the female bodies is called external fertilization
7. Fertilization:- The fusion of ovum and sperm is called fertilization
8. Foetus :- The stage of the embryo in which all the body parts are identifiable is called foetus
9. Internal Fertilization:- Fertilization that takes place inside the female body is called internal fertilization
10. Metamorphosis:- The transformation of the larva into adult through drastic changes is called metamorphosis
11. Oviparous Animals:- Animals such as hen, frog, lizard and butterfly which lay eggs are called oviparous animals
12. Sexual Reproduction:- Reproduction resulting from the fusion of male and female gametes is called sexual reproduction.
13. Sperms :- The testis produce male gametes called sperm
14. Viviparous animals:- Animals such as human beings, cows and dogs which give birth to young ones are called viviparous animals
15. Zygote :- The fertilized egg is called zygote
Chap 10 :- Reaching the age of Adolescence
1. Adam's apple :- At puberty, boys grow a larger voice box that appears as a bulging part of the throat. This is called Adam’s apple.
2. Adolescence :- period of life in which organism become capable to reproduce their offsprings.
3. Adrenalin :- Hormone that helps to adjust stress in a human body at the time of certain emotions like anger, embarrassment, etc. It is secreted by Adrenaline gland.
4. Balanced diet :- Balanced diet is a meal that includes adequate amount of proteins, carbohydrates, fats, vitamins and minerals.
5. Endocrine glands :- Ductless hormones which secrete hormones and released it into the bloodstream
6. Estrogen:- Female sex hormone that is secreted by ovaries.
7. Hormones:- Chemical substances that coordinate the activities of living organisms and also for their growth are called hormones.
8. Insulin:- Hormone produced by pancrease is called insulin.
9. Pituitary gland:- Gland which controls the release of other hormone glands in a human body, including the thyroid and adrenals, the ovaries and testicles.
10. Puberty:- The period in which rate at which general body growth begins to slow down and reproductive tissues begin to mature is called puberty.
11. Reproductive health:- A state of complete physical, mental and social well being in all aspects of reproduction.
12. Secondary sexual characters:- Secondary sexual characters refer to the external features that distinguish a male from a female.
13. Sex chromosomes:- The sex of baby is determined by a pair of chromosome called sex chromosomes.
14. Target site:- Endocrine glands release hormones into the bloodstream to reach a particular body part called target site.
15. Testosterone:- Male sex hormone that is secreted by testis
16. Thyroxine:- Hormone produces by thyroid gland is called thyroxine.
17. Voice box :- Sound box or larynx which begins to grow at puberty . It produces sounds.
Chapter 11 Force and Pressure
1. Atmospheric pressure:- The air all around us also exerts pressure. This is known as Atmospheric Pressure. The value of atmospheric pressure is very high.
2. Contact forces : Force that arises with the contact of 2 or more objects involved. Examples : Muscular force and Frictional Force
3. Electrostatic force is the force exerted by a charged body on another charged or uncharged body.
4. Force:-A push or a pull on an object is called a Force
5. Frictional Force is a force that acts on all moving objects by the surface which it is in contact with.
The Frictional force is always in the direction opposite to the applied force.
6. Gravitational : it is an attractive force between two massive bodies .
G= (gmM)/r2
7. Gravity:-force exerted by the earth on all objects on it. When a ball is thrown up, it falls to the ground because of gravity
8. Magnetic Force is a force that attracts certain metal objects (like iron and iron filings) towards a magnet.
9. Muscular force is the type of force wherein we use our physical strength to change the state of motion of an object. Eg: Man pushing a car, Bullocks pulling a cart of load, Cycling, Weight Lifting
10. Non-contact forces: Forces that arise without the contact of 2 or more objects involved. Examples: Magnetic Force, Electrostatic Force, Gravitational force
11. Force acting on unit area is called Pressure ie Pressure = Force/Area
12. Pull:-Pull refers to that force which tends to 'move the object towards' the direction of the force applied.
13. Push:-
Push refers to the force which tends to 'move the object away' from the direction of the force applied
Chap 12 :- Friction
1. Ball bearing :- Ball bearing is a device which consists of a ring of small metal balls. It is designed to make the moving parts of a machine to roll over each other rather than slide.
2. Drag :- Fluids (means liquids and gases) too exert friction on the objects. The frictional force exerted by fluids is called a drag
3. Fluid friction :- Fluids (means liquids and gases) too exert friction on the objects. The frictional force exerted by fluids is called fluid friction or drag
4. Friction:- Friction is a type of forces that opposes motion.It always acts in a direction opposite to that of the applied force.
5. Interlocking:- The irregularities on two surfaces tend to lock into each other . This is called interlocking.
6. Lubricants:- substances which make the surfaces smooth and thereby reduce friction are called lubricants.
7. Rolling friction:- when a body rolls over another surface is called Rolling Friction. The Rolling Friction is less that Sliding Friction.
8. Sliding friction:- when a body moves over another surface is called Sliding Friction
9. Static friction :- Static friction is friction between two or more solid objects that are not moving relative to each other.
Chap 13:- Sound
1. Amplitude:- The magnitude of maximum disturbance in the medium on either side of the mean value is called amplitude.
2. Audible:- A sound of 20Hz to 20,000 Hz that a human can hear is called audible range of sounds.
3. Eardrum:- The thin membrane present in the ear is called eardrum.
4. Hertz:- SI unit of frequency is called hertz
5. Larynx:- sound is produced by the vibration of an organ called voice box or larynx.
6. Loudness:- Amplitude determines the Loudness of sound. It is expressed in a unit called decibel (dB).
7. Noise:- Unpleasant sounds are called noise
8. Oscillation:- The motion in which object moves to and fro is called oscillation.
9. Pitch :-Perception of frequency of sound wave is called stillness of pitch. Frequency determines the shrillness or the pitch of the sound.
10. Shrillness:- Perception of frequency of sound wave is called stillness of pitch. Frequency determines the shrillness or the pitch of the sound.
11. Time period:- Time taken to complete one oscillation is called time period.
12. Vibration :- Rapid to and fro motion of an object is called vibration.
13. Voice box :- sound is produced by the vibration of an organ called voice box or larynx.
14. Wind pipe :- Pipe which help in gases exchange. The Larynx is situated at the upper end of windpipe.
Chap 14 Chemical effects of electric current
1. Electrode:-Electrodes are the metal rods which are dipped in liquids, to which cells are attached are called electrodes
2. Electroplating:-Process by which metals are coated with another metal to give it their lustrous appearance and still keep it cost effective.
Or
Process of depositing a layer of desired metal on another material by mean of electricity is called electroplating.
3. Good conductor:-The materials which conduct electricity are called good conductors of electricity. Eg: Iron, copper, aluminum, iron, human body etc
4. LED:- Light Emitting Diode. A device that produces a light on electrical and electronic equipment.
5. Poor conductor:-The materials which don't conduct electricity at all are bad conductors of electricity. Eg: plastic, glass, rubber.
Chap 15 Some Natural Phenomenon
1. Crust :- The uppermost layer of the earth is called crust.
2. Discharge:- The process of release of electric charges from a charged object to an uncharged object in contact with it , is called discharge.
3. Earth's plates:- The outermost layer of the earth is not in one piece but is fragmented . These fragments are called earth's plates
4. Earthquake:- It is a sudden shaking or trembling of the earth which lasts for a very short time is called earthquake
5. Electroscope:- A device that can be used to test whether an object is carrying charge or not , is called electroscope.
6 . Lightning:- The bright flash of light which we see in the clouds is called lightning.
Or
Lightning is an electric discharge in the atmosphere between oppositely charged clouds
7. Lightning conductor:- Lightening conductor is a device used to protect buildings from the effect of lightening.
8. Negative charge:- If an object gains electrons, it now has surplus number of electrons. Thus, this object becomes negatively charged.
9. Positive charge:- If an object loses some electron, it is left with surplus number of protons. Thus, this object becomes positively charged.
10. Richter scale:- The power of an earthquake is expressed in terms of a magnitude on a scale clleca the Richter scale
11. Seismograph:- An instrument which record seismic waves produce by tremors.
12. Thunder:- Thunder is the sound caused by lightning
13. Thunderstorm:- A rain-bearing cloud that also produces lightning is called thunderstorm.
14. Transfer of charge:- When certain objects are rubbed against another object, electrons may get transferred from one object to another.
15. Tsunami:- A tsunami is a very large and powerful wave. It is caused by earthquakes under the sea.
16. Tremor:- A relatively minor seismic shaking or vibrating movement.
Chap 16 light
1. Angle of incidence:-angle between the Incident ray and normal
2. Angle of reflection:-Angle between the reflected ray and normal
3.Blind spot:- Spot where rod and cone cells are absent so no image formed.
4. Braille:-The Braille script is an alphabet set used by the blind for reading and writing. Each Braille character is made up of a combination of 6 dots arranged in a matrix form.
5. Cones:-cells which are Sensitive to bright light
6. Cornea:-Outermost, transparent, thin membrane of eye ball.
Light enters into eye through cornea.
7. Diffusion or irregular reflection:-
When light falls on a rough surface (like a stone, your body, your clothes etc), all the parallel incident rays are not reflected parallel to each other. This is called Diffused Reflection.
8. Incident rays:-Ray of light that strike the surface.
9. Iris:-Dark muscular diaphragm that control the size of pupil.
Provide colour to eye.
10. Kaleidoscope:-A kaleidoscope is an optical instrument with two or more reflecting surfaces tilted to each other in an angle, so that one or more (parts of) objects on one end of the mirrors are seen as a regular symmetrical pattern when viewed from the other end, due to repeated reflection.
11. Lateral inversion:- In mirror left appears right and right appears left . This is called lateral inversion
12. Laws of reflection:-1. Angle of incidence= angle of reflection
2. Incident ray, reflected ray and the normal all lie on the same plane.
13. Pupil:It is the window of the eye.
Central aperture In iris.
Regulates and control the amount of light entering the eye
14 Reflected rays:-Ray of light sent back by the surface after reflection
15. Reflection:-Bouncing back of ray of light into the same medium after striking a polished surface such as mirror is called reflection of light
16 Regular reflection:- When light falls on a smooth uniform surface (like a mirror), all the parallel incident rays are reflected perfectly parallel. This is called Regular Reflection.
17 Retina:-Delicate membrane having enormous number of light sensitive cells. Lens image form on the retina.
18 Rods:- cells which are Sensitive to dim light
Chap 17 Stars and the solar system
1. Artificial Satellites:- Man made satellites revolving round the Earth are called artificial satellites
2. Asteroids:- large gap in between the orbits of Mars and Jupiter that is occupied by a large number of small objects that revolve around the Sun are called asteroids
3. Cassiopeia:- constellation in the notthern sky that looks like a distorted letter W or M
4. Celestial objects:- the stars , the planets, the moon and many other objects in the sky are called celestial objects.
5. Comets:- Comets are cosmic snowballs of frozen gases, rock and dust that orbit the Sun.
6. Constellations:- Group of stars that appear to form recognisable shapes.
7. Light year:- It is the distance travelled by light in one year.
8. Meteorites:- meteors that reaches the Earth is called a meteorite
9. Meteors:- Bright streaks of light in the sky or shooting stars are called meteors
10. Natural satellites:- A natural satellite is any celestial body in space that orbits around a larger body.
11. Orbit:- A planet has a definite path in which it revolves around the Sun . This path is called an orbit.
12. Orion:- constellation which has seven or eight bright stars. It is also called the hunter
13. Phases of moon:- The various shapes of the bright part of the moon as seen during a month are called phases of the moon.
14. Planets:- Celestial bodies that revolves around the Sun in a fixed path, are called planets
15. Pole star:- Pole star is the only star in the sky which appears stationary to an observer on Earth.
16. Remote sensing:- Remote sensing is the science of obtaining information about objects or areas from a distance, typically from aircraft or satellites.
17. Solar system:- A collection of the Sun, eight planets , asteroids ,comets and meteors.
18. Stars:- Stars are huge celestial bodies made mostly of hydrogen and helium that produce light and heat.
19. Ursa Major:- There are seven prominent stars that appears like a big ladle or a question mark is called Ursa major.
Chap 18 Pollution of Air and Water
1. Air pollution :- It is defined as contamination of air by impurities which may have a harmful impact on the living organisms and non living components.
2. Chemical contamination :- When industries release chemicals including arsenic , lead and fluoride into waterways , it is called chemical contamination. This leads to toxicity in plants and animals.
3. Global warming:- the average temperature of the earth atmosphere is gradually increasing. This is called global warming.
4.Green house effect:- The trapping of radiations by the earth's atmosphere is similar to that of green house. So the effect is called green house effect
5. Pollutants:- those substance which contaminate air and water.
6. Potable water:- water which is purified and fit for drinking is known as potable water.
7. Water pollution:- It is the contamination of water by substances harmful to life
