Question

A cylinder contains $10\, kg$ of gas at a pressure of $10^7\, N\, m^{-2}$. The quantity of gas taken out of the cylinder, if final pressure is $2.5 \times 10^6\, N\, m^{-2}$ is

• A. $9.5\, kg$
• B. $7.5\, kg$
• C. $14.2\, kg$
• D. zero

Answer 1

Answer: (B)

$\frac{P_{1}}{P_{2}} = \frac{\rho_{1}}{\rho_{2}} = \frac{m_{1}}{m_{2}}$
$m_{2} = \frac{P_{1}}{P_{2}} \times m_{1} = \frac{2.5\,\times\,10^{6}}{10^{7}}\times10 = 2.5\,kg$
Mass of gas taken out $= 10 - 2.5 = 7.5 \,kg$