WAEC Chemistry 2020 Paper

Concept:At constant temperature, a fixed mass of gas obeys Boyle's law: $P_1V_1 = P_2V_2$.Explanation:Given initial pressure $P_1 = 3P$ and initial volume $V_1 = V$.The final volume is increased to $V_2 = 2V$.Using Boyle's law, substitute the known values:$$(3P)(V) = P_2(2V)$$Simplify: $3PV = 2V P_2$.Cancel $V$ from both sides: $3P = 2P_2$.Solve for $P_2$:$$P_2 = \frac{3P}{2}$$So when the volume doubles, the pressure is halved.Answer:The final pressure is $\frac{3P}{2}$, which is equal to $1.5P$.