A 10.0 L flask contains 64 g of oxygen at $27^\circ C$. (Assume $O_2$ gas is behaving ideally). The pressure inside the flask in bar is (Given $R=0.0831\ L\ bar\ K^{-1}mol^{-1}$)

A 4.9

B 2.5

C 498.6

D 49.8

The answer is A.

Solution

$n_{O_2} = \frac{64}{32} = 2$ mol, V = 10 L, T = 300 K $PV = nRT \Rightarrow P = \frac{2 \times 0.0831 \times 300}{10}$ P = 4.9 bar

Concept pressure from ideal gas equation

3 questions from this chapter have appeared across 3 exam years.