Question

what is a greenhouse gas? (1 point)
a gas at higher temperature than the surrounding atmosphere
any gas in the troposphere that absorbs and re - emits infrared radiation
any gas in earths atmosphere
a gas that forms a physical barrier to block escaping heat

Explanation:

To determine the correct definition of a greenhouse gas, we analyze each option:

• The first option is incorrect because a greenhouse gas's definition is not about its temperature relative to the surrounding atmosphere.
• The second option is correct. Greenhouse gases in the troposphere (and other atmospheric layers) absorb and re - emit infrared radiation, which is a key mechanism in the greenhouse effect.
• The third option is incorrect as not all gases in Earth's atmosphere are greenhouse gases (e.g., nitrogen is not a greenhouse gas).
• The fourth option is incorrect because greenhouse gases do not form a physical barrier; they absorb and re - emit radiation to trap heat.

Answer:

B. any gas in the troposphere that absorbs and re - emits infrared radiation