Q.

The molecules of a given mass of a gas have r.m.s. velocity of 200 ms-1 at 27°C and 1.0×105 Nm-2 pressure. When the temperature and pressure of the gas are respectively, 127°C and 0.05×105 Nm-2, the r.m.s. velocity of its molecules in ms-1 is               [2016]
 

1 10023  
2 1003  
3 1002  
4 4003  

Ans.

(4)

As, vrms=3kBTm

   v27v127=27+273127+273=300400=32

or   v127=23×v27=23×200ms-1=4003ms-1