class 8 worksheet on reproduction, sound and pressure.

I. Fill in the blanks:

(i) _________ is the smallest mammal.

(ii) When the eggs of a frog hatch, _________ come out.

(iii) The eggs of fish are hatched into _________.

(iv) _________ the yellow round part of an egg.

(v) The _________ lays the biggest egg in the world.

(vi) _________ feed their babies with their own milk.

(vii) The larva that hatches out of a butterfly egg looks like a worm. It is called a _________.

II. Write ‘Yes’ for right and ‘No’ for wrong statements.

(i) All the living beings do not reproduce their own kind.  No

(ii) All animals feed their babies with their own milk. No
(iii) The young ones of a cat is puppy. No
(iv) Mammals are warm-blooded. Yes

(v) A frog goes through four stages in its life cycle. Yes

(vi) The larva of a butterfly is called caterpillar. Yes

(vii) All the living beings take care of their young ones. No

(viii) Some animals lay thousands of eggs at a time. Yes

III. Answer the following questions:
(i) What is reproduction?

(ii) Who are mammals?

(iii) Name the smallest mammals?

(iv) Name two animals that lay their eggs in water.

(v) Name any five egg-laying animals.

(vi) Name two animals that do not take care for their young ones.

(vii) What are the life-stages of a butterfly?

                                        sound

Fill in the blanks :

1. Time taken by an object to complete one oscillation is called _______________.

2. Loudness is determined by the _______________________of vibration.

3. The unit of frequency is ________________________.

4. Unwanted sound is called ______________________.

5. Shrillness of a sound is determined by the __________________________.

6. The number of oscillation in one second is called ____________________.

7. The hearing range of human ear is _____________

8. Sound cannot travel in __________________.

9. Sound can travel in _____________________.

10. The pitch of sound depends on __________________.

Choose the correct answer :

1. Ear drum is a part of ____________________ [ sound producing organ or hearing organ]

2. The voice box is also called _________________ [ Larynx / mouth]

3. Large amplitude of sound vibrations will produce __________________________ [ Loud sound / slow sound]

4. Voice of which of following is likely to have minimum frequency _____________________________ [ Baby girl / A woman]

5. The unit of loudness is ________________ ( decibel / Hertz)

Answer the following :

1. Name the sound producing organ in human.

2. How does sound travel from one place to another ?

3. How is sound produced ?

4. What do you mean by musical sound ?

5. How does the amplitude affect the loudness of vibration?

FORCE AND PRESSURE

1. S.I unit of pressure is ____________.

2. The amount or the strength of force is called its_______________.

3. Pressure in solid depends upon ________________ and ____________.

4. Pressure in liquids depends upon _____________ and ______________.

5. Force generated by moving of non living materials is called ______________.

6. Give 2 examples of contact forces.

7. Name the scientist who invented a pump to extract air from a vessel.

8. Name the force which acts upon another body without any connector.

9. Name the type of force involved in the following.

a) To pick your school bag. b) To collect scrap iron from garbage.

c) To push or pull a loaded trolley ay supermarket.

d) Flying of seeds away from each other in plastic bag when gently rubbed.

10. Name the device used to measure pressure in fluids.

11. How much force is required to lift a mass of 1Kg (10N/1N).

12. A rolling ball stops after sometime due to (gravitational force/ Frictional force).

13. When 2 forces are applied at the same point but in opposite directions the net force is equalto the (sum/ difference) of forces acting separately.

14. Force used to stretch the spring is (muscular force/ magnetic force)

15. Application of force brings the change in

a) shape and size of object ( b)speed and direction of object (c) position of object (d) all the above