MHT CET Chemistry Question (2026) — Solution

Step-by-step solution

The balanced chemical equation for the reaction is: C_2H_4(g) + HCl(g) C_2H_5Cl(g) Initial volumes: V_ C_2H_4 = 200 mL V_ HCl = 150 mL Total initial volume V_i = 200 + 150 = 350 mL. Since the reaction occurs at constant pressure and temperature, the volumes of gases are directly proportional to their number of moles. Here, HCl is the limiting reagent. Volume of C_2H_4 reacted = 150 mL Volume of C_2H_4 remaining = 200 - 150 = 50 mL Volume of C_2H_5Cl formed = 150 mL Total final volume V_f = 50 + 150 = 200 mL. Change in volume V = V_f - V_i = 200 - 350 = -150 mL = -0.15 L. The work done during the reaction at constant pressure is given by: W = -P V Substituting the values: W = -1 bar (-0.15 L ) = 0.15 L bar Since 1 L bar = 100 J , we get: W = 0.15 100 J = 15 J Answer: 15 J