Question

A gas has an initial pressure of 450 mmHg and a volume of 5 L. Find the final pressure in kPa when the volume is increased to 15 L assuming the temperature of the system is constant.

• A. 20
• B. 30
• C. 40
• D. 15

Answer 1

The correct option is A 20

Since, temperature of the system is constant
Using, boyle's law, $P_1{V}_1=P_2{V}_2$
$P_1$ = 450 mmHg $V_1$ = 5 L $V_2$ = 15 L
$P_2$ = $\frac{450\times 5}{15}$ = 150 mm Hg
Now, 1 mmHg = 133.32 Pa
Therefore 150 mmHg = 19998 Pa ~ 20 kPa