The rms speed of a gas can be calculated using the following rule:
Vrms = sqrt[(3RT) / M] where
R is the gas constant = 8.314 J K^−1 mol^−1
T is the temperature = 32.5 + 273 = 305.5 degree kelvin
M is the molar mass = 2*14 = 28 grams = 0.028 kg
Substitute with the givens in the equation to get the rms speed as follows:
Vrms = sqrt [(3*8.314*305.5) / 0.028]
Vrms = 521.665 m/sec