# Molar Mass of unknown gas

1. A sample bulb contained 0.712 g H2 (g) at a certain temperature and pressure. Under the same conditions of temperature and pressure, the bulb can hold 13.0 g of an unknown gas. What is the molar mass of the unknown gas?

Obtaining H2 volume from the ideal gas law (assuming STP) and then using that volume to obtain the unknown gas density (with STP) is the correct way to obtain the molar mass?

I would appreciate some help

Thank you.