General Science 7th Class Chapter 12 Earth and Space Solved Exercise

 

General Science

7th Class

Chapter 12

Earth and Space

Questions

12.1 Encircle the correct option.

1. An object is attracted towards the Earth due to:

a. pull        b. push        c. gravity        d. friction

2. Which of the following is the major cause of tides?

a. heating oceans by the Sun

b. gravitational pull of the Moon

c. earthquakes on the surface of the ocean floor

d. change in  the wind direction

3. Seasons on the Earth's surface are caused by:

a. spin motion of the Earth about its own axis

b. orbital motion of the Earth around the Sun

c. tilt of Earth on its axis

d. the tilt of Earth and orbital motion of the Earth around the Sun

4. What is the season on 22nd June in the southern hemisphere?

a. spring        b. autumn        c. summer        d. winter

5. The weight of an object on Earth's surface is 600 N. What will be its weight on the Moon's surface?

a. 600 N        b. 300 N        c. 200 N        d. 100 N

6. The tides are highest during:

a. day        b. night        c. half Moon        d. full Moon

12.2 Write short answers.

1. An athlete can jump 5 metre up on the Earth, how high he can jump on the Moon?

Ans.

The force of gravity on Moon surface is 1/6 of that on Earth. If an athlete jumps 5 metre high on Earth, he can jump 30 metres on the Moon.

2. A person can throw a shot put 2 meters away. How long will be his throw on the Moon's surface?

Ans.

If a person can throw a shot 2 metres away at the earth surface, his throw on the moon surface will be 12 metres.

3. Which of the Sun or Moon has a greater pull on the ocean's water? Give reason of your answer.

Ans.

Moon has greater pull on oceans water than that of sun. The reason is that moon is nearer to earth surface than sun.

4. Differentiate force exerted by the Moon on the waters at the near surface and that exerted on the water of far surface.

Ans.

On the near side of Earth, (the side facing moon) the gravitational force of the moon pulls the ocean's water towards it, creating on bulge. On the far side of the Earth, inertia dominates, creating a second bulge. In this way, two bulges of water are formed.

5. What will be the season in Australia when there is summer in Pakistan?

Ans.

Pakistan is in northern hemisphere, and Australia is in Sothern hemisphere. If there is Summer in Pakistan, there will be winter in Australia.