• # question_answer 78) A closed container contains equal number of oxygen and hydrogen molecules at a total pressure of 740 mm. If oxygen is removed from the system then the pressure will A)  Become 1/9 of 740 mmB)  Become half of 740 mmC)  Remains unchangedD)  Become double of 740 mm

According to Dalton's law of partial pressure as number of moles of ${{O}_{2}}$ and ${{H}_{2}}$are same. $\Rightarrow P{{o}_{2}}={{p}_{{{H}_{2}}}}=p$ Total pressure $P=P{{o}_{2}}+{{p}_{{{H}_{2}}}}+2p$ $p=\frac{P}{2}=\frac{740\,mm}{2}$ = 370 mm The pressure of ${{H}_{2}}$ gas is 370 mm. Hence, the correct option is [b].