What is the density (in g/L) of hydrogen gas at 23.0 degrees Celsius and a pressure of 1670 psi?

Answer 1

Use PV = nRT to calculate n, number of moles H2 gas. Don't forget to change 1670 psi to atmospheres and temperature to Kelvin. Use 1 L for volume.
Convert n to mass (moles = grams/molar mass).
Then use mass = volume x density to determine density.