GEOLOGY

Detailed explanation-1: -(a) Due to the revolution, the length of days and nights varies at a place at different times of the year. (b) Revolution causes a change of seasons. (c) It helps in the location of Tropic of Cancer and Tropic of Capricorn due to the fact that Sun rays fall vertical here. (d) The altitude of the mid-day Sun changes.

Detailed explanation-2: -The rotation of the earth causes day and night. As the earth is spherical in shape, only one half of it is illuminated by the sun at a time. The other half remains dark. The illuminated portion of the earth experiences day and the other part of the earth experiences night.

Detailed explanation-3: -Answer is (d) the axis of rotation of the earth is tilted with respect to the plane of its orbit. Explanation: Axis of rotation of the earth is not perpendicular to the plane of its orbit. The tilt is responsible for the change of seasons on earth.

Detailed explanation-4: -The earth’s spin axis is tilted with respect to its orbital plane. This is what causes the seasons. When the earth’s axis points towards the sun, it is summer for that hemisphere. When the earth’s axis points away, winter can be expected.