A closed vessel contains 8g of oxygen and 7g of nitrogen. The total pressure is 10 atm at a given temperature. If now oxygen is absorbed by introducing a suitable absorbent the pressure of the remaining gas in atm will be:

From Dalton's law, final pressure of the mixture of nitrogen and oxygen

$$\begin{gathered} P=P_1+P_2=\frac{{\mu }_{1}RT}{V}+\frac{{\mu }_{2}RT}{V} \\ =\frac{m_1}{M_1}\frac{RT}{V}+\frac{m_2}{M_2}\frac{RT}{V}=\frac{8}{32}\frac{RT}{V}+\frac{7}{28}\frac{RT}{V}=\frac{RT}{2V} \\ \Rightarrow 10=\frac{RT}{2V} ...( i ) \end{gathered}$$

When oxygen is absorbed then for nitrogen let pressure is

$$\begin{gathered} P=\frac{7}{28}\frac{RT}{V} \\ \Rightarrow P=\frac{RT}{4V} ...( ii ) \end{gathered}$$

From equation (i) and (ii) we get pressure of the nitrogen

P = 5 atm