Question

A $2.24L$ cylinder of oxygen at NTP is found to develop a leakage. When the leakage was plugged, the pressure dropped to $570mm$ of $Hg$. The number of moles of gas that escaped will be :

• A. $0.025$
• B. $0.050$
• C. $0.075$
• D. $0.09$

Answer 1

The correct option is A $0.025$

Original pressure of Hg $=760mmHg$

Drop-in pressure $=570mmHg$

Change in pressure $=760-570=190mmHg$

$=\frac{190}{760}atm$

From Ideal gas law equation:

$PV=nRT$

$n=\frac{PV}{RT}$

$n=\frac{190\times 2.24}{760\times 0.082\times 273}$

$=0.025$ moles

Hence, option $A$ is correct.