If the r.m.s. velocity of a gas at a given temperature (Kelvin scale) is 300m/sec. What will be the r.m.s. velocity of a gas having twice the molecular weight and half the temperature on Kelvin scale =
(a) 300 m/sec
(b) 600 m/sec
(c) 75 m/sec
(d) 150 m/sec
