Question

A quantity of gas is collected in a graduated tube over the mercury. The volume of the gas at ${20}^{\circ }C$ is $50.0mL$ and the level of the mercury in the tube is $100mm$ above the outside mercury level. The barometer reads $750mm$. Volume at $STP$ is :

• A. $39.8mL$
• B. $40mL$
• C. $42mL$
• D. $60mL$

Answer 1

The correct option is A $39.8mL$

According to given,
Effective pressure $=750-100=650torr$

So now, $\frac{P_1{V}_1}{T_1}=\frac{P_2{V}_2}{T_2}$

$650\times 50/293$ = $760\times V/273$

$V=39.8ml$

So, the correct option is $A$