Question

If $1$ litre of gas $A$ is $600$mm and $0.5$ L of a gas $B$ at $800$ mm are taken in a $2L$ bulb. The resulting pressure is:

• A. $1500$ mm
• B. $1000$ mm
• C. $2000$ mm
• D. $500$ mm

Answer 1

The correct option is D $500$ mm

For gas $A$,

P = $600mm$

V = $1L$

$\text{No. of moles of A =}\frac{PV}{RT}=\frac{600\times 1}{RT}=\frac{600}{RT}$

For gas $B$,

P = $800mm$

V = $0.5L$

$\text{No. of moles of B =}\frac{PV}{RT}=\frac{800\times 0.5}{RT}=\frac{400}{RT}$

$\text{Total no. of moles =}\frac{600}{RT}+\frac{400}{RT}=\frac{1000}{RT}$

$\Rightarrow \frac{P_{final}\times V_{final}}{RT}=\frac{1000}{RT}$

$V_{final}=2L$

$P_{final}\times 2=1000$

$\Rightarrow P_{final}=500mm$

Hence, correct option is $D$.