what is the volume of 1 gram of hydrogen gas at STP

STP =standard temperature and pressure:

T= 273.15 K
p=10⁵Pa

μ for hydrogen =2 g/mol= 0.002 kg/mol
R=8.31 J/mol•K.
m=1g=0.001 kg
From
pV=mRT/μ

V= mRT/μp