When the temperature of a gas is raised from 30° C to 90° C, the percentage increase in the r.m.s. velocity of the molecules will be :
Vrms ∝ T T1=30 + 273 = 303 K T2=90 + 273 = 363 KV1V2=T1T2 = 303363V2 − V1V1× 100= 363303−1 × 100 = 9.5%