Q. Which of the following absorbs part of the insolation and preserves earth’s radiated heat?

[A] Oxygen

[B] Nitrogen

[C] Water vapour

[D] Carbon-dioxide

Answer: C

The amount of solar energy reaching the Earth is 70 percent. The surface of the Earth absorbs 51 percent of the insolation. Water vapor and dust account for 16 percent of the energy absorbed. Most of the terrestrial radiation is absorbed by the water vapor in the atmosphere and some by other gases (about 8 percent is radiated directly to outer space). This radiant energy is re-radiated in the atmosphere horizontally and vertically.

Source: ICSE book