Which of the following substances is most likely to be a liquid at room temperature?
a. formaldehyde, h₂coh₂co
b. fluoromethane, ch₃fch₃f
c. hydrogen cyanide, hcn
d. hydrogen peroxide, h₂o₂h₂o₂
e. hydrogen sulfide, h₂s

The correct answer is d.hydrogen peroxide H₂O₂H₂O₂

Explanation:

Substances can be found in nature in different aggregation states.

Agreggation states can be liquid, gas or solid.

The problem asks about which substance can be found in room temperature as liquid. Each subtances has different physical and chemical properties that determines in which state you can find them at room temperature.

Hydrogen peroxide is the only substance listed that is in liquid state at room temperature, all other substances are in gas state at room temperature.

i believe you are right for all except the 3rd ( look at sqdancefan his answer is much better)