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..