Read the Assertion and Reason below and choose the correct option. — Chemical Equilibrium Chemistry Question

💡 Solution & Explanation

A decrease in volume instantly increases the molar concentration ($n/V$) and partial pressures of all gases. To relieve the pressure, the equilibrium shifts backward (towards fewer gaseous moles), increasing the moles of A and decreasing the moles of C. However, this backward shift will also form more B(s). Therefore, Statement II is incorrect because it falsely claims there is "no change in the moles of B(s)". Statement I is correct because the equilibrium shift only partially undoes the initial concentration spike caused by the volume drop. Therefore, correct answer is C.