Question

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

Answer 1

Answer: (B)

2u

Answer 2

$\frac { U _ { 1 } } { U _ { 2 } } = \sqrt { \frac { n _ { 1 } T _ { 1 } } { n _ { 2 } T _ { 2 } } } = \sqrt { \frac { n \times T } { 2 n \times 2 T } } = \sqrt { \frac { 1 } { 4 } } = \frac { 1 } { 2 }$

$U _ { 2 } = 2 U _ { 1 } = 2 U$