The root mean square velocity of one mole of a monoatomic gas having molar mass M is Urms. The relation between the average kinetic energy (E) of the gas and Urms is :
Urms=√2EM
Average K.E. of gas per mole E=32RT⇒ RT=2E3
Urms=√3RTM Therefore Urms=√3×2E3M=√2EM