Question

The volume of an air bubble becomes three times as it rises from the bottom of a lake to its surface. Assuming atmospheric pressure to be 75 cm of Hg and the density of water to be 1/10 of the density of mercury, the depth of the lake is

• A. 5m
• B. 10m
• C. 15m
• D. 20m

Answer 1

The correct option is C

15m

$P_1{V}_1=P_2{V}_2\Rightarrow (P_0+h\rho g)V=P_0\times 3V$

$\Rightarrow h\rho g=2P_0\Rightarrow h=\frac{2\times 75\times 13.6\times g}{\frac{13.6}{10}\times g}=15m$