Q. Consider the following statements:
- Without the atmosphere, temperature would be well below freezing point everywhere on the Earth’s surface.
- Heat absorbed and trapped by the atmosphere maintains our planet’s average temperature.
- 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
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Answer & Explanation:
✅Correct Answer: (c) I, II and III
Explanation:
Statement I – Correct
If the Earth had no atmosphere, it would lose heat very rapidly to outer space. As a result, surface temperatures would fall to well below the freezing point across almost the entire planet, with extreme differences between daytime and nighttime temperatures—similar to conditions on the Moon.
Statement II – Correct
The atmosphere plays a vital role in maintaining Earth’s temperature through the natural greenhouse effect. Incoming solar radiation warms the Earth’s surface, which then emits heat as infrared (longwave) radiation. The atmosphere absorbs and re-radiates part of this outgoing heat, keeping the global average surface temperature around 15 °C, instead of far below zero.
Statement III – Correct
Certain atmospheric gases—known as greenhouse gases—are especially effective at absorbing and trapping infrared radiation. These include carbon dioxide (CO₂), water vapour (H₂O), methane (CH₄), and nitrous oxide (N₂O). Their heat-trapping ability is fundamental to Earth’s climate system and temperature regulation.
Why Other Options Are Incorrect
- Options (a), (b), and (d) are incorrect because each excludes at least one statement that is factually correct.
- Since all three statements are correct, the only valid answer is Option (c).