Question

The molecular weights of O₂ and N₂ are 32 and 28 respectively. At 15°C, the pressure of 1 gm O₂ will be the same as that of 1 gm N₂ in the same bottle at the temperature

• A. – 21°C
• B. 13°C
• C. 15°C
• D. 56.4°C

Answer 1

Answer: (A)

– 21°C

Answer 2

For 1gm gas $PV = rT = \left( \frac{R}{M} \right).T$

Since P and V are constant

Ž $T \propto M$Ž $\frac{T_{N_{2}}}{T_{O_{2}}} = \frac{M_{N_{2}}}{M_{O_{2}}}$

Ž $\frac{T_{N_{2}}}{(273 + 15)} = \frac{28}{32}$Ž $T_{N_{2}} = 252K$ = – 21°C