Which of the following gases is not impacted at all by infrared radiation?

• A. H_2O
• B. N_2
• C. CH_4
• D. CO_2

Answer: (B)

Verified step by step guidance

1. Understand that infrared (IR) radiation interacts with gases by causing changes in their molecular vibrations or rotations, which requires the molecule to have a changing dipole moment during these motions.
2. Recall that molecules like H_2O, CH_4, and CO_2 have polar bonds or molecular structures that allow them to absorb IR radiation because their vibrations change the dipole moment.
3. Recognize that N_2 is a homonuclear diatomic molecule with no permanent dipole moment and symmetric vibrations, so it does not absorb infrared radiation.
4. Conclude that because N_2 does not absorb IR radiation, it is not impacted by it, unlike the other gases listed.
5. Therefore, the gas not impacted at all by infrared radiation is N_2.