Question

Which substance is a gas at room temperature and atmospheric pressure?

Answer 1

Answer:

Explanation:

A) Hg is mercury, a metal that is mostly liquid at STP (Standard Temp and Pressure), though some small portion of it will be gaseous in a closed container.

B) CH Methylidyne radical is a gas

It is not a stable compound because carbon has four valence electrons and only one of those is kept occupied by the hydrogen atom.

If this is supposed to be CH₄ which is methane, then also a gas at STP

C) C₂H₅OH is ethanol which is mostly a liquid at STP, though some small portion of it will be gaseous in a closed container.

D) H₂O is water and will be mostly liquid at STP, though some small portion of it will be gaseous in a closed container.