At constant T and constant volume, argon is added to the equilibrium 2SO2(g) + O2(g) 2SO3(g). Which is correct?

Q_c = K_c remains true and the amounts of all gases are unchanged

K_c increases because the total pressure increases

Q_c < K_c and the equilibrium shifts forward

Q_c = K_c remains true and the amounts of all gases are unchanged

Q_c > K_c and the equilibrium shifts backward

JEE Main levelSingle correct optionDifficulty 2 of 3ce189

At constant $T$ and constant volume, argon is added to the equilibrium $2 SO X_{2} (g) + O X_{2} (g) 2 SO X_{3} (g)$ . Which is correct?

At constant volume, the concentrations of

SO X_{2}

O X_{2}

and

SO X_{3}

do not change when argon is added, so

Q_{c}

stays equal to

K_{c}

. Total pressure rises but the partial pressures of reacting gases do not, hence no shift.