Class 7 Science - Chapter Light NCERT Solutions | Mark 'T' if the statement i

State two differences between a convex and a concave lens.

David is observing his image in a plane mirror. The 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

Give one use each of a concave and a convex mirror.

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.

Match the items given in Column I with one or more items of Column II.

Column I                                          Column II
(a) A plane mirror                              (i) Used as a magnifying glass.
(b) A convex mirror                           (ii) Can form image of objects spread over a large area.
(c) A convex lens                              (iii) Used by dentists to see enlarged image of teeth.
(d) A concave mirror                         (iv) The image is always inverted and magnified.                                                                                                                    (e) A concave lens                            (v) The image is erect and of the same size as the object.
                                                         (vi) The image is erect and smaller in size than the object.

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 view 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

Find out the letters of English alphabet or any other language known to you in which the image formed in a plane mirror appears exactly like the letter itself. Discuss your findings.

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

What is a virtual image? Give one situation where a virtual image is formed.

Which type of lens forms always a virtual image?

State similarities and differences between the laboratory thermometer and the clinical thermometer.

State differences between acids and bases.

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

Name the elements that determine the weather of a place.

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 ———.

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

Why does an athlete breathe faster and deeper than usual after finishing the race?

Match structures given in Column I with functions given in Column II.

Column I                           Column II
(i) Stomata                        (a) Absorption of water
(ii) Xylem                           (b) Transpiration
(iii) Root hairs                    (c) Transport of food
(iv) Phloem                        (d) Transport of water
                                          (e) Synthesis of carbohydrates

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 _____________.

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.

Describe the steps involved in getting clarified water from wastewater.

Outline your role as an active citizen in relation to sanitation.

State similarities and differences between the laboratory thermometer and the clinical thermometer.

Explain the factors responsible for the depletion of water table.

State two experiences that made you think that air exerts pressure (other than those given in the text).

Indicate the type of climate of the following areas:

(a) Jammu and Kashmir: _________________________________
(b) Kerala: ____________________________________________
(c) Rajasthan: __________________________________________
(d) North-east India: _____________________________________

Match the items in Column I with those in Column II:
Column I                             Column II
(a) Yeast                             (i) Earthworm
(b) Diaphragm                    (ii) Gills
(c) Skin                               (iii) Alcohol
(d) Leaves                          (iv) Chest cavity
(e) Fish                               (v) Stomata
(f) Frog                               (vi) Lungs and skin
                                           (vii) Tracheae

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

Why is transport of materials necessary in a plant or in an animal? Explain.

Does transpiration serve any useful function in the plants? Explain.