Question

$10g$ of gas at atmospheric pressure is cooled from ${273}^{\circ }C$ to $0^{\circ }C$ keeping the volume constant; its pressure would become :

• A. $\frac{1}{2}atm$
• B. $\frac{1}{273}atm$
• C. $2atm$
• D. $273atm$

Answer 1

Answer: (A)

$\frac{1}{2}atm$

At constant volume, $\frac{P_2}{P_1}=\frac{T_2}{T_1}$
The initial pressure $P_1=1$ atm

The initial temperature $T_1=273{}^{o}C=273+273K=546K$.
The final pressure $P_2=?$

The final temperature $T_2=0{}^{o}C=273K$.
$\frac{P_2}{1}=\frac{273}{546}$

$P_2=\frac{1}{2}$ atm

Hence, the correct option is A.