NEET-XII-Physics
neet 2020 questions with solutions year:2020
- #4A cylinder contains hydrogen gas at pressure of 249 kPa and temperature `` 27^\circ\,C `` . Its density is : `` (R = 8.3\,J\,mol^{-1}K^{-1} `` )
(A) `` 0.5 \,kg/m^3 ``
(B) `` 0.2 \,kg/m^3 ``
(C) `` 0.1 \,kg/m^3 ``
(D) `` 0.02 \,kg/m^3 ``
digAnsr: BAns : We can express, an ideal gas equation as
`` \frac{P}{\rho}=\frac{R.T}{Mw} ``
`` \Rightarrow \rho=\frac{pMw}{RT} ``
`` =\frac{249 \times 10^{3}\times 2 \times 10^{-3}}{8.314 \times 300} ``
`` =0.199 ``
`` \Rightarrow \rho=0.2 kg/m^{3} ``