Diatomic elements form two-atom molecules at room temperature

Steps:

• List common diatomic gases: hydrogen (H₂), nitrogen (N₂), oxygen (O₂), fluorine (F₂), chlorine (Cl₂).
• Exclude halogens beyond fluorine and non-gases like bromine (Br₂, liquid) and iodine (I₂, solid).
• Note noble gases like helium and neon exist as single atoms (monatomic).
• Match options to this list, selecting the one with three diatomic gases.

Why C is correct:

• Nitrogen (N₂), oxygen (O₂), and fluorine (F₂) are nonmetals that pair up as stable diatomic molecules due to their high electronegativity and incomplete octets, forming gases at room temperature.

Why the others are wrong:

• A: Helium exists as monatomic He, not diatomic.
• B: Neon exists as monatomic Ne, not diatomic.
• D: Helium exists as monatomic He, not diatomic.

Final answer: C