WAEC Chemistry 2021 Paper

Concept:The ideal gas equation, $PV = nRT$, connects pressure, volume, temperature, and moles of gas.Explanation:From the question, the known values are $P = 10\ \mathrm{atm}$, $V = 8.2\ \mathrm{dm}^3$, $T = 320\ \mathrm{K}$, and $R = 0.082\ \mathrm{atm}\ \mathrm{dm}^3\ \mathrm{mol}^{-1}\ \mathrm{K}^{-1}$.Rearrange the ideal gas equation $PV = nRT$ to solve for $n$:$$n = \frac{PV}{RT}$$Substitute the given values into the equation:$$n = \frac{10 \times 8.2}{0.082 \times 320}$$Calculate the numerator and denominator:$$n = \frac{82}{26.24} = 3.125\ \mathrm{mol}$$Therefore, the number of moles is approximately $3.13\ \mathrm{mol}$.Answer:$3.13$ moles (Option C).