Question

To what tempreture should the hydrogen at ${327}^{\circ }C$ be cooled at constant pressure, so that root mean square velocity of its molecules become half of its previous value

• A. - 123°C
• B. 123°C
• C. - 100°C
• D. 0°C

Answer 1

The correct option is A

- 123°C

$v=\sqrt{\frac{3RT}{M}}\frac{V_1}{\sqrt{T_1}}=\frac{V_2}{\sqrt{T_2}}\frac{v_1}{v_2}=\sqrt{\frac{T_1}{T_2}}4=\frac{600}{T_2}=150K=-123{}^{0}C$