JAMB Chemistry 2019 Paper

Concept:The pressure, volume, and temperature of an ideal gas are linked by the combined gas law.This allows the final temperature to be found from the initial and final conditions.Explanation:Write the initial conditions: $V_1 = 200\ \mathrm{cm}^{3}$, $T_1 = 27^\circ\mathrm{C} + 273 = 300\ \mathrm{K}$.Let the initial pressure be $P_1$, so the final pressure is $P_2 = 2P_1$.The final volume is given as $V_2 = 150\ \mathrm{cm}^{3}$.Use the combined gas equation: $\frac{P_1V_1}{T_1} = \frac{P_2V_2}{T_2}$.Substitute the values: $\frac{P_1 \times 200}{300} = \frac{2P_1 \times 150}{T_2}$.Cancel $P_1$: $\frac{200}{300} = \frac{300}{T_2}$.Solve for $T_2$: $T_2 = 450\ \mathrm{K}$.Convert to Celsius: $T_2 = 450 - 273 = 177^\circ\mathrm{C}$.The temperature increase required is $177^\circ\mathrm{C} - 27^\circ\mathrm{C} = 150^\circ\mathrm{C}$.Answer:A. $150^\circ\mathrm{C}$