You do not turn moles into volume. A mole is a quantity of a substance. OK when I teach this I get the point across this way:
How many roses are in a dozen roses? 12 right
How many tires are in a dozen tires? 12 right
How many eggs in a dozen eggs? 12 right
So a mole contains exactly 6.022 x 10^23 objects or things.
A mole of tires has 6.022 x 10^23 tires
A mole of roses contains 6.022 x 10^23 roses
A mole of eggs has 6.022 x 10^23 eggs
A mole of ions has 6.022 x 10^23 ions in it
A mole of atoms has 6.022 x 10^23 atoms.....Do you get it?
Now for your chemistry problem you need to apply the Ideal Gas Law and the rule that a 1 mole of an ideal gas occupies a volume of 1 Liter at STP....
Here you do not have 1.0 mole you have 0.1 mole of gas and you have STP and STP means standard temperature and pressure....25 C and 1 atm...use appropriate units.
Look at the data they give you...write down what STP iis: they are specified temperature and pressure conditions....then look at the moles they give....it is not 1.0...it is a factor of 10 less it is 0.10 mole of hydrogen.
Use PV = nRT
Rearrange: V = (nRT/P)
Plug in your data and solve.....make sure all your units are in the same system..