JEE Main · 2023 · 13 Apr 2023 · Shift 2 · Environmental Chemistry

Greenhouse gases are those whose molecules absorb and re-emit infrared radiation. Water vapour is the most abundant of them, and ozone also absorbs strongly in the infrared, so both of these qualify. Molecular iodine and molecular hydrogen are homonuclear molecules whose vibrations produce no change in dipole moment, so they are infrared-inactive and are not greenhouse gases. The greenhouse gases in the list are therefore water vapour and ozone only.