Sure, I can help you with that.
The molar mass of a gas is the mass of one mole of that gas. One mole of any gas occupies the same volume under standard conditions, so we can use this to calculate the molar mass of X.
We know that 9.60 g of X occupies the same volume as 0.30 g of hydrogen. Since hydrogen has a molar mass of 1 g/mol, this means that 9.60 g of X is the same as 0.30 mol of hydrogen.
So, the molar mass of X is 9.60 g / 0.30 mol = 32 g/mol.
In other words, one mole of X has a mass of 32 grams.
Here is the calculation in a simpler form:
Molar mass of X = mass of X / moles of X
= 9.60 g / 0.30 mol
= 32 g/mol