Given, r.m.s speed of a gaseous molecule is xm∕s at a pressure patm. We know that, Kinetic theory of gas r.m.s. speed =√
3RT
M
We know pV=RT Then r.m.s. speed =√
3pV
M
As temperature is constant. So, pV is constant. Hence, r.m.s. speed is also constant. If the pressure is double at constant temperature, there is no change in r.m.s. speed.