Which of the following statements are correct in respect of greenhouse gases?…

Concept

Greenhouse classification in climate science is based on interaction with outgoing long-wave infrared radiation and the resulting atmospheric heat retention. For this exam item, the relevant convention is the principal/direct greenhouse-gas classification reflected in the official key; short-lived species whose main climate influence is indirect are treated separately.

Application

1. The visible-colour claim confuses the name of the effect with optical appearance. Greenhouse classification concerns radiative behaviour, while many greenhouse gases are colourless.

2. The thermal-radiation claim states the governing mechanism: greenhouse gases absorb and re-emit part of Earth’s outgoing long-wave infrared radiation.

3. The water-vapour claim identifies a major natural greenhouse gas with broad infrared absorption bands.

4. The global-warming claim gives the climatic consequence: increased greenhouse-gas concentrations strengthen atmospheric heat retention and raise global temperature.

5. The ammonia claim falls outside the principal/direct classification used by the official key. Atmospheric ammonia is short-lived, and standard climate inventories treat its main influence through indirect aerosol and chemical pathways.

Cross-check and contrast

Applying this criterion retains the thermal-radiation, water-vapour, and warming claims while excluding the visible-colour and ammonia claims.

• The combination that also includes the visible-colour claim retains an optical-name misconception.

• The combination joining visible colour, water vapour, and ammonia includes two claims outside the governing classification and omits both the radiative mechanism and its warming consequence.

• The combination containing visible colour, thermal absorption, warming, and ammonia omits water vapour and includes two claims outside the governing classification.

Therefore, the correct option value is ‘B, C, D Only.’