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Q.1. State True (T) or false (F).
(i) Axis of the earth is an imaginary line about which the earth rotates. True
(ii) Earth takes exactly 365 days to revolve around the sun. False
(iii) Day and Night on the Earth occurs due to rotation of the Earth. True
(iv) On 21st march, the Tropic of Capricorn receives direct rays of the sun as the South Pole tilts towards it. False
(v) Every fourth year, February is of 29 days instead of 28 days. True
(vi) When there is spring in the Northern Hemisphere and summer in the Southern Hemisphere. False
Q.2. What is the shape of the Earth?
Earth is spherical in shape.
Q.3. Differentiate between rotation and revolution of earth.
Q.4. When Christmas is celebrated in Australia?
Christmas is celebrated in Australia in the summer season.
Q.5. Which motion of the earth causes change in seasons?
Revolution of the earth causes change in seasons.
Q.6. Why do the poles experience about six months of day and night?
The Poles experience about six months of day and six months of night because of the tilt of the Earth on its axis. When the North Pole is tilted towards the Sun, it experiences continuous daylight for six months and when the South Pole is away from the sun, it experiences continuous
darkness for six months.
Q.7. How long does it take the earth to complete one rotation around its axis?
The earth takes about 24 hours to complete one rotation around its axis.
Q.8. Why do seasons occur?
The seasons are caused by the tilt of the Earth's rotational axis away or toward the sun as it travels around the sun in its orbit.
Q.9. When do the sun rays fall directly on the equator?
On 21st March and September 23rd, direct rays of the sun fall on the equator.
Q.10. Why days and nights are not of equal length?
Days and nights are not equal length because of the inclined axis of the earth. As earth is tilted at an angle of 23.4°, days are longer in summers than in winters.
Q.11. What causes change in seasons?
Seasons change due to the change in the position of the earth around the sun.
Q.12. Fill in the blanks.
(i) The earth receives light from the sun.
(ii) The earth takes about 24 hours to complete one rotation around its axis.
(iii) The period of rotation is known as the earth day.
(iv) On 23rd September, it is autumn season in the Northern Hemisphere and spring season in the Southern Hemisphere.
(v) The portion facing the sun experiences day while the other half away from the sun experiences night.
(vi) The axis of the earth makes an angle of 66½ degree with its orbital plane.
(vii) Australia lies in Southern Hemisphere. viii. The longest day and the shortest night at these places occur on 21st june.
Q.13. Why areas near the poles receive less heat?
The areas near the poles receive less heat as the rays of the sun are slanting.