He is a gas and to find the volume, the gas law can be used
PV = nRT
P= Pressure of the gas (Pa)
V = Volume of the gas (m³)
n = Moles (mol)
R = Universal gas constant (8.314 J mol⁻¹ K⁻¹)
T = Temperature in Kelvin (K)
P= 785 mm Hg = 1.05 x 10⁵ Pa
n = mass / molar mass
= 2.04 g / 4.00 g mol⁻¹
= 0.51 mol
R = 8.314 J mol⁻¹ K⁻¹
T = 273 + 100 K = 373 K
By adding those values to the above equation volume can be calculated.
hence volume = nRT / P
V = 0.51 x 8.314 x 373 / 1.05 x 10⁵
V = 15.06 x 10⁻³ m³
