anytime a compound starts with hydrogen
(h) as its cation, the compound must
be.

a. a base
b. an acid
c. covalent

The gas would begin to expand, and eventually the can would burst or explode.

The answer is b because c don't explain why the moths are on them and it isn't a because as we know only one species of moth does this

Molarity is moles of solute over liters of solution. idk if that is what you are talking about, but you can convert moles of solute to grams of solute using dimensional analyzes by using molar mass found on the periodic table.