At what temperature would 41.9 g of oxygen in a 40.0-liter tank produce a pressure of 15.2 psi?
find moles of O2: 41.9/32= ...
then, PV=nRT or T=PV/nR
you have n, Pressure, Volume
find temp
triple check your units on R You need R in atm, liters, psi, temp in K