Consider the following statements :

I. Without the atmosphere, temperature would be well below freezing point everywhere on the Earth’s surface.
II. Heat absorbed and trapped by the atmosphere maintains our planet’s average temperature.
III. Atmosphere’s gases, like carbon dioxide, are particularly good at absorbing and trapping radiation.

Which of the statements given above are correct?

(a) I and III only
(b) I and II only
(c) I, II and III
(d) II and III only

The correct answer is (d) II and III only.

Explanation

Statement I: Incorrect.Without an atmosphere, the Earth would be like the Moon. The side facing the sun would become extremely hot (well above the boiling point of water), and the side in darkness would become extremely cold (well below freezing). The atmosphere’s job is to trap heat and distribute it, preventing these massive temperature extremes. The word “everywhere” makes this statement false.
Statement II: Correct.This is an accurate description of the greenhouse effect. The atmosphere traps some of the outgoing heat (infrared radiation) from the Earth’s surface, which keeps the planet’s average temperature stable and warm enough to support life (around 15°C or 59°F).
Statement III: Correct.This statement identifies the specific agents of the greenhouse effect. Gases like carbon dioxide ([latex]CO_2[/latex]), methane ([latex]CH_4[/latex]), and water vapor ([latex]H_2O[/latex]) are known as “greenhouse gases” because their molecular structure is particularly good at absorbing and re-radiating infrared radiation (heat), thereby “trapping” it in the atmosphere.