Q. The rms speed of $N_{2}$ molecules in a gas is $u$. If the temperature is doubled and the nitrogen molecules dissociate into nitrogen atoms, the rms speed becomes
A) $u/2$
B) $2u$
C) $4u$
D) $14u$
Explanation
(b)
$\frac{u_{1}}{u_{2}} = \sqrt{\frac{n_{1}T_{1}}{n_{2}T_{2}}} = \sqrt{\frac{n \times T}{2n \times 2T}} = \sqrt{\frac{1}{4}\ } = \frac{1}{2}$
$\therefore\ u_{2} = 2u_{1}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.