Back exercise
Chap 1
Q.6. Fill in the blanks:
(a) Green plants are called ________________ since they synthesise their own food.
(b) The food synthesised by the plants is stored as ________________ .
(c) In photosynthesis solar energy is captured by the pigment called ________________
(d) During photosynthesis plants take in ________________ and release ________________ .
Ans. (a) autotrophs (b) starch (c) chlorophyll (d) carbon dioxide, oxygen
Q.7. Name the following:
(i) A parasitic plant with yellow, slender and tubular stem.
(ii) A plant that has both autotrophic and heterotrophic mode of nutrition.
(iii) The pores through which leaves exchange gases.
Ans. (i) cuscuta (ii) Insectivorous plant (iii) Stomata
Q.8. Tick the correct answer:
(a) Amarbel is an example of:
(i) Autotroph (ii) Parasite (iii) Saprotroph (iv) Host
(b) The plant which traps and feeds on insects is:
(a) Cuscuta (ii) China rose {iii) Pitcher plant (iu) Rose
Ans. (a) (ii) Parasite (b) (iii) Pitcher plant
Q.9. Match the items given in Column I with those in Column II:
Chlorophyll --- > Leaf
Nitrogen ----- > Rhizobium
Cuscuta ------ > Parasite
Animals ------ > Heterotrophs
Insects -------- > Pitcher plant
Q.10. Mark T’ if the statement is true and ‘F’ if it is false:
(i) Carbon dioxide is released during photosynthesis. (T/F)
(ii) Plants which synthesise their food themselves are called saprotrophs. (T/F)
(iii) The product of photosynthesis is not a protein. (T/F)
(iv) Solar energy is converted into chemical energy during photosynthesis. (T/F)
Ans. (a) F (ii) F (iii) T (iu) T
Q.11.Choose the correct option from the following.
Which part of the plant takes in carbon dioxide from the air for photosynthesis?
(i) Root hair (ii) Stomata (iii) Leaf veins (iv) Sepals
Ans. (ii) Stomata
Q.12. Choose the correct option from the following:
Plants take carbon dioxide from the atmosphere mainly through their:
(i) Roots (ii) Stem (iii) Flowers (iv) Leaves
Ans. (iv) Leaves
Chapter :- 2
Q.1.Fill in the blanks:
(a) The main steps of nutrition in humans are ___________, ___________, ___________ , ___________ and ___________
(b) The largest gland in the human body is ___________.
(c) The stomach releases hydrochloric acid and ___________ juices which act on food.
(d) The inner wall of the small intestine has many finger-like outgrowths called ___________
(e) Amoeba digests its food in the ___________ .
Ans.(a) ingestion, digestion, absorption, assimilation, egestion
(b) liver (c) digestive (d) villi (e) food vacuole.
Q.2. Mark ‘T’ if the statement is true and ‘F’ if it is false:
(a) Digestion of starch starts in the stomach. (T/F)
(b) The tongue helps in mixing food with saliva. (T/F)
(c) The gall bladder temporarily stores bile. (T/F)
(d) The ruminants bring back swallowed grass into their mouth and chew it for sometime. (T/F)
Ans. a) F (b) T (c) T (d) T
Q.3.Tick (S) mark the correct answer in each of the following:
(a) Fat is completely digested in the
(i) stomach (ii) mouth (in) small intestine (iv) large intestine
(b) Water from the undigested food is absorbed mainly in the:
(i) Stomach (ii) Food pipe (iii) Small intestine (iv) Large intestine
Ans.(a) (iii) Small intestine (b) (iv) Large intestine
Q.4.Match the items of column I with those given in column II:
Food components ---- > Products of digestion
Carbohydrates ------ > Sugar
Proteins --------> Amino acids
Fats ---------- > Fatty acids and glycerol
Q.9. Which part of the digestive canal is involved in:
(i) Absorption of food ________ .
(ii) Chewing of food ________ .
(iii) Killing of bacteria ________ .
(iv) Complete digestion of food ________ .
(v) Formation of faeces ________ .
Ans. (i) Small intestine (ii) Mouth (iii) Stomach (iv) Small intestine (v) Large intestine
Q.11. Match the items of Column I with suitable items in Column II.
Salivary gland----- > Saliva secretion
Stomach------ > Acid release
Liver ------- > Bile juice secretion
Rectum ----- > Storage of undigested food
Small intestine ---- > Digestion is completed
Large intestine ------ > Absorption of faeces.
Chap 3:-
Q.2. The silkworm is (a) a caterpillar (b) a larva. Choose the correct option.
(i) (a) (ii) (b) (iii) both (a) and (b) (iv) neither (a) nor (b)
Ans. (iii) both (a) and (b).
Q.3. Which of the following does not yield wool?
(i) Yak (ii) Camel (iii) Goat (iv) Woolly dog
Ans. (iv) Woolly dog
Q.5. Given below is a sequence of steps in the processing of wool. Which are the missing steps? Add them.
Shearing, ________ , sorting,________, __________
Ans. Shearing, scouring, sorting, picking out of burrs, colouring, rolling.
Q.7. Out of the following, which are the two terms related to silk production? Sericulture, floriculture, moriculture, apiculture and silviculture.
Hints: (i) Silk production involves cultivation of mulberry leaves and rearing silkworms. (ii) Scientific name of mulberry is Morus alba.
Ans. (i) Sericulture (ii) Moriculture
Q.8 Match the words of Column 1 with those given in Column 2:-
Scouring --------> cleaning sheared skin
Mulberry leaves ------> Food of silk worm
Yak -------- > Wool yielding animal.
Cocoon--------- >Yields silk fibres
Chap :- 4
Q.3.Fill in the blanks
The hotness of an object is detetmined by its ____________ .
(b) Temperature of boiling water cannot be measured by a ____________ thermometer.
(c) Temperature is measured in degree ____________ .
(d) No medium is required for transfer of heat by the process of ____________.
(e) A cold steel spoon is dipped in a cup of hot milk. It transfers heat to its other end by the process of ____________
(f) Clothes of ___________ colours absorb heat better than clothes of light colours.
Ans. (a) temperature (b) clinical (c) Celsius (d) radiation (e) conduction (f) dark
4. Match the following :-
(i) Land breeze blows during - > night
(ii) Sea breeze blows during - > day
(iii) Dark coloured clothes are preferred during ------- > winter
(iv) Light coloured clothes are preferred during ----- > summer
Q.8. One litre of water at 30°C is mixed with one litre of water at 50°C. The temperature of the mixture will be:
(a) 80°C (b) More than 50°C but less than 80°C
(c) 20°C (d) Between 30°C and 50°C
Ans.(d) Between 30°C and 50°C.
Q.9. An iron ball at 40°C is dropped in a mug containing water at 40°C. The heat will:
(a) flow from iron ball to water.
(b) not flow from iron ball to water or from water to iron ball.
(c) flow from water to iron ball.
(d) increase the temperature of both.
Ans. (b) not flow from iron ball to water or from water to iron ball
Q.10. A wooden spoon is dipped in a cup of ice-cream. Its other end:
(a) becomes cold by the process of conduction
(b) becomes cold by the process of convection
(c) becomes cold by the process of radiation
(d) does not become cold
Ans.(d) does not become cold.
Q.11.Stainless steel pans are usually provided with copper bottoms. The reason for this could be that:
(a) copper bottom makes the pan more durable
(b) such pans appear colourful
(c) copper is a better conductor of heat than the stainless steel
(d) copper is easier to clean than the stainless steel
Ans.(c) copper is better conductor of heat than the stainless steel
Chap :-5
Q.2.Ammonia is found in many household products, such as window cleaners. It turns red litmus blue. What is its nature?
Ans.Ammonia has basic nature
Q.6.Mark ‘T’ if the statement is true and ‘F’ if it is false:
(i) Nitric acid turns red litmus blue. (T/F)
(ii) Sodium hydroxide turns blue litmus red. {T/F)
(iii) Sodium hydroxide and hydrochloric acid neutralise each other and form salt and water. (T/F)
(id) Indicator is a substance which shows different colours in acidic and basic solutions. . (T/F)
(v) Tooth decay is caused by the presence of a base. (T/F)
Ans.(1) F (ii) F (iii) T (iv) T (V) F
Q. 11. Consider the following statements:
(a) Both acids and bases change colour of all indicators.
(b) If an indicator gives a colour change with an acid, it does not give a change with a base.
(c) If an indicator changes colour with a base, it does not change colour with an acid.
(d) Change of colour in an acid and a base depends on the type of the indicator. Which of these statements are correct?
(i) All four (ii) (a) and (d) (iii) (b) and (c) (iv) only (d)
Ans. (ii) (a) and (d)
Chap 6
Q.1.Classify the changes involved in the following processes as physical or chemical changes:
(a) Photosynthesis
(b) Dissolving sugar in water
(c) Burning of coal
(d) Melting of wax
(e) Beating aluminium to make aluminium foil
(f) Digestion of food
Ans.(a) Chemical change (b) Physical change
(c) Chemical change (d) Physical change
(e) Physical change (/) Chemical change
Q.2.(a) Cutting a log of wood into pieces is a chemical change. (True/ False)
(b) Formation of manure from leaves is a physical change. (True/ False)
(c)Iron pipes coated with zinc do not get rusted easily. (True/ False)
(d)Iron and rust are the same substances. (True/ False)
(e)Condensation of steam is not a chemical change. (True/ False)
Ans. (a)False
Correct statement: Cutting a log of wood into pieces is an irreversible physical change.
(b)False
Correct statement: Formation of manure from leaves is a chemical change.
(c) True
(d)False
Correct statement: Iron and rust are two different chemical substances.
(e)True
Q.3.Fill in the blanks in the following statements:
(a) When carbon dioxide is passed through lime water, it turns milky due to the formation of _________.
(b) The chemical name of baking soda is .
(c) Two methods by which rusting of iron can be prevented are __________ and __________
(d) Changes in which only ____________ properties of a substance change are called physical changes.
(e) Changes in which new substances are formed are called _____________ changes..
Ans. (a)calcium carbonate
(b) sodium hydrogen carbonate
(c) painting or greasing, galvanisation
(d) physical
(e) chemical
Q.11. The gas we use in the kitchen is called liquified petroleum gas (LPG). In the cylinder it exists as a liquid. When it comes out from the cylinder it becomes a gas (Change- A) then it bums (Change-B). The following statements pertain to these changes. Choose the correct one.
(i) Process-A is a chemical change.
(ii) Process-B is a chemical change.
(iii) Both processes A and B are chemical changes.
(iv) None of these processes is a chemical change.
Ans. (ii) Process-B is a chemical change.
Q.12.Anaerobic bacteria digest animal waste and produce biogas (Change-A). The biogas is then burnt as fuel (Change-B). The following statements pertain to these changes. Choose the correct one.
(i) Process-A is a chemical change.
(ii) Process-B is a chemical change.
(iii) Both processes A and B are chemical changes.
(iv) None of these processes is a chemical change.
Ans.(iii) Both processes A and B are chemical change
Chap :- 7
Q.3.Fill in the blanks
(i) The average weather taken over a long time is called __________
(ii) A place receives very little rainfall and the temperature is high throughout the year, the climate of that place will be ________ and _________
(iii) The two regions of the earth with extreme climatic conditions are __________ and ____________
Ans. climate of the place (ii) hot, dry (iii) polar, tropical regions
Q.4.Indicate the type of climate of the following areas:
(a) Jammu and Kashmir:
(b) Kerala:,
(c) Rajasthan:
(d) North-east India:
Ans.(a) Jammu and Kashmir—moderately hot and moderately wet climate.
(b) Kerala—very hot and wet climate.
(c) Rajasthan—hot and dry climate.
(d) North-east India—The north eastern India receives rain for a major part of the year, hence wet climate.
Q.5.Which of the two changes frequently, weather or climate?
Ans.Weather
Q.6.Followings are some of the characteristics of animals:
(i) Diets heavy on fruits
(ii) White fur
(iii) Need to migrate
(iv) Loud voice
(v) Sticky pads on feet
(vi) Layer of fat under skin
(vii) Wide and large paws
(viii) Bright colours
(ix) Strong tails
(x) Long and large beak
For each characteristic indicate whether it is adaptation for tropical rainforests or polar regions. Do you think that some of these characteristics can be adapted for both regions?
Ans:-
(i) Diets heavy on fruits --------------- > Tropical rainforest
(ii) White fur --- > Polar region
(iii) Need to migrate --->Polar region
(iv) Loud voice----------- >Tropical rainforest
(v) Sticky pads on feet------------- >Tropical rainforest
(vi) Layer of fat under skin------------------ >Polar region
(vii) Wide and large paws----------------- >Polar region
(viii) Bright colours ------ >Tropical rainforest
(ix) Strong tails --------- >Tropical rainforest
(x) Long and large beak ----------------------- >Tropical rainforest
Q.10.Choose the correct option which answers the following question:
A carnivore with stripes on its body moves very fast while catching its prey. It is likely to be found in:
(i) polar regions (ii) deserts
(iii) oceans (iv) tropical rainforests
Ans. (iv) tropical rainforests
Q.11.Which features adapt polar bears to live in extremely cold climate?
(i) A white fur, fat below skin, keen sense of smell.
(ii) Thin skin, large eyes, a white fur.
(iii) A long tail, strong claws, white large paws.
(iv) White body, paws for swimming, gills for respiration.
Ans.(iv) A white fur, fat below skin, keen sense of smell.
Q.12.Which option best describes a tropical region?
(i) hot and humid
(ii) moderate temperature, heavy rainfall (iii) cold and humid (iv) hot and dry
Ans.(i) Hot and humid
Chap :-8
1.Fill the missing word in the blank spaces in the following statements:
(a) Wind is ___________air.
(b) Winds are generated due to _________ heating on the earth.
(c) Near the earth’s surface _________ air rises up whereas _________ air comes down.
(d) Air moves from a region _________of pressure to a region _________of pressure.
Ans.(a) moving (b) uneven
(c) warm, cooler (d) high, low
Q.8. Which one of the following places is unlikely to be affected by cyclone?
(i) Chennai (ii) Mangalore
(iii) Amritsar (iv) Puri
Ans.(iv) Amritsar
Q.9.Which of the statements given below is correct?
(i) In winter the winds flow from the land to the ocean.
(ii) In summer the winds flow from the land towards the ocean.
(iii) A cyclone is formed by a very high-pressure system with very high-speed winds revolving around it.
(iv) The coastline of India is not vulnerable to cyclones.
Ans.(i) In winter the winds flow from the land to the ocean.
Chapter 9
Tick the most suitable answer in question 1 and 2.
In addition to the rock particles, the soil contains
(i) Air and water
(ii) Water and plants
(iii) Minerals, organic matter, air and water
(iv) Water, air and plants
Answer:
In addition to the rock particles, the soil contains
(iii) Minerals, organic matter, air and water.
Q2. The water holding capacity is the highest in
(i) Sandy soil
(ii) Clayey soil
(iii) Loamy soil
(iv) Mixture of sand and loam
Answer:
The water holding capacity is the highest in
(ii) Clayey soil
Q3. Match the items in Column I with those in Column II:
1. A home for living organisms----------> All kinds of soil
2. Upper layer of soi----- > Dark in colour
3. Sandy soil----------> Large particles
4. Middle layer of soil--------> lesser amount of humus
5. Clayey soil -----> small particles and packed light.
Chapter 10
Tick the correct answer:
(a) In cockroaches, air enters the body through
(i) lungs
(ii) gills
(iii) spiracles
(iv) skin
Answer: (iii) spiracles
(b) During heavy exercise, we get cramps in the legs due to the accumulation of
(i) carbon dioxide
(ii) lactic acid
(iii) alcohol
(iv) water
Answer: (ii) lactic acid
(c) Normal range of breathing rate per minute in an average adult person at rest is:
(i) 9 – 12
(ii) 15 – 18
(iii) 21 – 24
(iv) 30 – 33
Answer: (ii) 15 – 18
(d) During exhalation, the ribs
(i) move outwards
(ii) move downwards
(iii) move upwards
(iv) do not move at all
Answer: (ii) move downwards
Mark T if the statement is true and F if it is false:
(i) During heavy exercise the breathing rate of a person slows down. (T/ F)
(ii) Plants carry out photosynthesis only during the day and respiration only at night. (T/ F)
(iii) Frogs breathe through their skins as well as their lungs. (T/ F)
(iv) The fishes have lungs for respiration. (T/ F)
(v) The size of the chest cavity increases during inhalation. (T/ F)
Answer:
(i) F
(ii) F
(iii) T
(iv) F
(v) T
Chapter 11
Q.1.Match structures given in Column I with functions given in Column II
1. Stomata. -------> Transpiration
2. Xylem-----> Transport of water
3. Root hairs----- > Absorption of water
4. Phloem-----> Transport of food
Q.2.-Fill in the blanks :
(i) The blood from the heart is transported to all parts of the body by the _____________
(ii) Haemoglobin is present in ___________ cells.
(iii) Arteries and veins are joined by a network of ___________ .
(iv) The rhythmic expansion and contraction of the heart is called ___________
(v) The main excretory product in human beings is ___________
(vi) Sweat contains water and .
(vii) Kidneys eliminate the waste materials in the liquid form called .
(viii) Water reaches great heights in the trees because of suction pull caused by .
Ans.(i) arteries (ii) red blood cells • (in) capillaries (iv) heartbeat (v) urea (vi) salts (vii) urine (viii) transpiration.
Q.3.Choose the correct options:
(a) In plants, water is transported through
(i) Xylem (ii) Phloem (iii) Stomata (iv) Root hair
(b) Water absorption through roots can be increased by keeping the plants
(i) In the shade (ii) in dim light (iii) under the fan (iv) covered with a polythene bag
Ans.(a) (i) Xylem {b) (iii) under the fan
Chap 12
Q.1.Fill in the blanks:
(a) Production of new individuals from the vegetative part of parent is called ___________.
(b) A flower may have either male or female reproductive parts. Such a flower is called _______.
(c) The transfer of pollen grains from the anther to the stigma of the same or of
another flower of the same kind is known as __________.
(d) The fusion of male and female gametes is termed as ____________ .
(e) Seed dispersal takes place by means of ________ and __________.
Ans. (a) vegetative reproduction (b) unisexual flower (c) pollination (d) fertilization (e) wind, water
Q.9.Match items in Column I with those in Column II
1. Bud ---> yeast
2. Eyes----> potato
3. Fragmentation-----> Spirogyra
4. Wings------ > Maple
5. Spores ------ > Bread mould
Tick the correct answer:
(a) The reproductive part of a plant is the
(i) leaf (ii) stem (iii) root (iv) flower
(b) The process of fusion of the male and the female gametes is called
(i) fertilisation (ii) pollination (iii) reproduction (iv) seed formation
c) Mature ovary forms the
(i) seed (ii) stamen (iii) pistil (iv) fruit
(d) A spore producing plant is
(i) rose (ii) bread mould (iii) potato (iv) ginger
(e) Bryophyllum can be reproduced by its
(i) stem (ii) leaves (iii) roots (iv) flower
Ans.(a) (iv) flower (b) (i) fertilisation (c) (iv) fruit (d) (ii) bread mould (e) (ii) leaves
Chap 13
Q.1.Classify the following as motion along a straight line, circular or oscillatory motion :
(i) Motion of your hands while running.
(ii) Motion of a horse pulling a cart on a straight road.
(iii) Motion of a child in a merry-go-round. •
(iv) Motion of a child on a see-saw.
(v) Motion of the hammer of an electric bell.
(vi) Motion of a train on a straight bridge.
Ans.(i) Oscillatory motion
(ii) Linear motion
(iii) Circular motion
(iv) Oscillatory motion
(v) Oscillatory motion
(vi) Linear motion
Q.2.Which of the following are not correct?
(i) The basic unit of time is second.
(ii) Every object moves with a constant speed.
(iii) Distances between two cities are measured in kilometers.
(iv) The time period of a given pendulum is not constant.
(v) The speed of a train is expressed in m/h
Ans. (ii), (iv), (v)
.8. Which of the following relations is correct?
(i) Speed = Distance Time
(ii) Speed = Distance/Time
(iii)Speed – Time/Distance
(iv)Speed = 1/Distance Time
Ans. (ii) Speed = Distance/Time is correct
Q.9.The basic unit of speed is:
(i) km/min (ii) m/min (iii) km/h (iv) m/s
Ans. (iv) m/s
10.A car moves with a speed of 40 km/h for 15 minutes and then with a speed of 60 km/h for the next 15 minutes. The total distance covered by the car is:
(i) 100 km (ii) 25 km (iii) 15 km (iv) 10 km
Ans.(ii) 25 km
Q.11.Suppose the two photographs, shown in fig. 13.1 and fig. 13.2 of NCERT had been taken at an interval of 10 seconds. If a distance of 100 metres is shown by 1 cm in these photographs, calculate the speed of the blue car.
Ans.0.1 cm/s or 10 m/s
Q.12.Fig 13.10 shows the distance-time graph for the motion of two vehicles A and B. Which one of them is moving faster?
Ans. ‘A’ is moving faster.
Q.13.Which of the following distance-time graphs shows a truck moving with speed which is not constant?
Ans. (iii)
Chap 14
Q.8.Fill in the blanks:
(a) Longer line in the symbol for a cell represents its ___________terminal
(b) The combination of two or more cells is called a ____________.
(c) When current is switched ‘on’ in a room heater, it ___________.
(d) The safety device based on the heating effect of electric current is called a _____________.
Ans.(a) positive (b) battery (c) becomes red hot and emits heat (d) fuse.
Q.9.Mark ‘T’ if the statement is true and ‘F’ it is a false:
(a) To make a battery of two cells, the negative terminal of one cell is connected to the negative terminal of the other cell. [T/F]
(b) When the electric current through the fuse exceeds a certain limit , the fuse wire melts and breaks. [T/F]
(c) An electromagnet does not aatract a piece of iron. [T/F]
(d) An electric bell has an electromagnet. [T/F]
Ans. (a) F (b) T (c) F (d) T
Chap 15
Q.1.Fill in the blanks:
(a) An image that cannot be obtained on a screen is called ___________ .
(b) Image formed by a convex is __________ always virtual and smaller in size.
(c) An image formed by a __________ mirror is always of the same size as that of the object.
(d) An image which can be obtained on a screen is called a __________ image.
(e) An image formed by a concave __________ cannot be obtained on a screen.
Ans.(a) virtual image (b) mirror (c) plane (d) real (e) lens
Q.2.Mark ‘T’ if the statement is true and ‘F’ if it is false:
(a) We can obtain an enlarged and erect image by a convex mirror. (T/F)
(b) A concave lens always form a virtual image. (T/F)
(c) We can obtain a real, enlarged and inverted image by a concave mirror. (T/F)
(d) A real image cannot be obtained on a screen. (T/F)
(e) A concave mirror always form a real image. (T/F)
Ans. a) F (b) T (c) T (d) F (e) F
Q.3. Match the items given in Column I with one or more items of Column II
1. A plane mirror ---- >The image is erect and of the same size as the object
2. A convex mirror ---- > Can form image of objects spread over a large area
3. A convex lens --- > Used as magnifying glass
4. A concave mirror---- >used by dentist to see enlarged image of teeth
5. A concave lens----- > The image is erect and smaller in size than the object.
Q.9. Which type of mirror can form a real image?
Ans. Concave mirror can form a real image.
Q.10. Which type of lens forms always a virtual image?
Ans. Concave lens always forms a virtual image.
Choose the correct option in Questions 11-13:
Q.11. A virtual image larger than the object can be produced by a
(i) concave lens (ii) concave mirror (iii) convex mirror (iv) plane mirror
Ans. (ii) concave mirror
Q.12. David is observing his image in a plane mirror. Die distance between the mirror and his image is 4 m. If he moves 1 m towards the mirror, then the distance between David and his image will be
(i) 3 m (ii) 5 m (iii) 6 m (iv) 8 m
Ans. (iii) 6 m
Q.13. The rear view mirror of a car is a plane mirror. A driver is reversing his car at a speed of 2 m/s. The driver sees in his rear mew mirror the image of a truck parked behind his car. The speed at which the image of the truck appears to approach the driver will be
(i) 1 m/s (ii) 2 m/s (iii) 4 m/s {iv) 8 m/s
Ans. (ii) 4 m/s
Chap 16
Mark ‘T’ if the statement is true and ‘F’ if it is false:
(a) The freshwater stored in the ground is much more than that present in the rivers and lakes of the world. (T/F)
(b) Water shortage is a problem faced only by people living in rural areas. (T/F)
(c) Water from rivers is the only source for irrigation in the fields. (T/F)
(d) Rain is the ultimate source of water. (T/F)
Ans. (a) T (b) F (c) F (d) T
Q.6.Fill in the blanks with the appropriate answers: .
(a) People obtain groundwater through and .
(b) Three forms of water are solid, and .
(c) The water bearing layer of the earth is .
(d) The process of water seepage into the ground is called .
Ans.(a) wells, hand pumps
(b) liquid, gas
(c) aquifer
(d) infiltration
Q.7.Which one of the following is not responsible for water shortage?
(i) Rapid growth of industries
(ii) Increasing population
(iii) Heavy rainfall
(iv) Mismanagement of water resources
Ans.(iii) heavy rainfall
Q.8.Choose the correct option. The total water
(i) in the lakes and rivers of the world remains constant.
(ii) under the ground remains constant.
(iii) in the seas’and oceans of the world remains constant.
(iv) of the world remains constant.
Ans.(iv) of the world remains constant.
Chap 17
Q.7.Fill in the blank:
(a) The insects, butterflies, honeybees and birds help flowering plants in .
(b) A forest is a purifier of and .
(c) Herbs form the layer in the forest.
(d) The decaying leaves and animal droppings in a forest enrich the .
Ans. (a) pollination (b) water, air (c) lowest (d) soil as humus.
Q.11.Which of the following is not a forest product?
(i) Gum (ii) Plywood (iii) Sealing wax (iv) Kerosene
Ans.(iv) Kerosene
Q.12.Which of the following statements is not correct?
(i) Forests protect the soil from erosion.
(ii) Plants and animals in a forest are not dependent on one another.
(iii) Forests influence the climate and water cycle.
(iu) Soil helps forests to grow and regenerate.
Ans.(ii) Plants and animals in a forest are not dependent on one another.
Q.13.Micro-organisms act upon the dead plants to produce
(i) sand (ii) mushrooms (iii) humus (iu) wood
Ans. (i) Humus
Chap 18
.1. Fill in the blanks:
(a) Cleaning of water is process of removing __________
(b) Wastewater released by houses is called __________.
(c) Dried __________ is used as manure.
(d) Drains get blocked by __________ and __________.
Ans.(a) pollutants (b) sewage (c) sludge (d) (d) chemicals, kitchen waste
.7. Name two chemicals used to disinfect water.
Ans. Chlorine and ozone
Study the following statements about ozone:
(a) It is essential for breathing of living organisms.
(b) It is used to disinfect water.
(c) It absorbs ultraviolet rays.
(d) Its proportion in air is about 3%.
Which of these statements are correct?
(i) (a), (b) and (c) (ii) (b) and (c) (iii) (a) and (d) (iv) All four
Ans. (ii) (b) and (c)
