Question

The temperature of the hydrogen at which the average speed of its molecules is equal to that of oxygen molecules at a temperature of 31°C, is

• A. – 216°C
• B. – 235°C
• C. – 254°C
• D. – 264°C

Answer 1

Answer: (C)

– 254°C

Answer 2

$v_{av} = \sqrt{\frac{8RT}{\pi M}}$Ž$T \propto M$ $\lbrack\because v_{av},R \rightarrow \text{constan}\rbrack$

Ž$\frac{T_{H_{2}}}{T_{O_{2}}} = \frac{M_{H_{2}}}{M_{O_{2}}}$Ž$\frac{T_{H_{2}}}{(273 + 31)} = \frac{2}{32}$

Ž$T_{H_{2}} = 19K = - 254{^\circ}C$