The temperature of the diatomic hydrogen gas sample is increased to 100∘c. the root-mean-square speed vrms for diatomic hydrogen at 100∘c is:

In physical chemistry, there is an equation for the root mean square speed, or also known in abbreviated form of rms. The equation is:

rms = √(3RT/M)
where
R = 8.314 J/mol-K
T is the absolute temp
M is the molar mass; For H₂, M = 0.002 kg/mol

rms = √(3(8.314)(100+273)/(2))
rms = 2,156.78 m/s

U whay do you need with?

The correct answer is "hydrogen".