Let T1=120K, T2=480K
The root mean square velocity of the gas molecule at 120K= v
The root mean square velocity of the gas molecule at 480K=v2
The ratio of the root mean square velocity at 120K to the ratio of the root mean square velocity at 480K= v/v2
v/v2=
⇒v/v2=
⇒v/v2=
⇒v/v2=1/2
⇒v2=2v
Vrms- root mean square velocity.
Therefore the root mean square speed of gas molecules 480 K, will be 2v