Thank you for reporting, we will resolve it shortly
Q.
A cylinder contains $10\, kg$ of gas at pressure of $10^{7} N / m ^{2} .$ The quantity of gas taken out of the cylinder, if final pressure is $2.5 \times 10^{6} N / m ^{2}$ will be (temperature of gas is constant)
Intital mass of the gas $m_{1}=10\, kg$
Initial pressure $P_{1}=10\, N / m ^{2}$
Final pressure $P_{2}=2.5 \times 10^{6} N / m ^{2}$
According to kinetic theory of gases
$P V=\frac{1}{3} m c^{-2}$
or $P \propto m$
Hence, $\frac{P_{1}}{P_{2}}=\frac{m_{1}}{m_{2}}$
or $\frac{10^{7}}{2.5 \times 1^{6}}=\frac{10}{m_{2}}$
or $m_{2}=2.5\, kg$
Hence, quantity of gas taken out from the cylinder is
$10-2.5=7.5\, kg$