The incorrect match in the following is:

🧠 $\Delta G^\circ = -RT\ln K$: the sign of $\Delta G^\circ$ directly fixes whether $K > 1$ or $K < 1$ If $\Delta G^\circ < 0$, then $\ln K > 0$, so $K > 1$ (product-favoured). If $\Delta G^\circ > 0$, then $K < 1$.

🗺️ Checking each match (a) $\Delta G^\circ < 0$, $K > 1$ → Correct. ✓ (b) $\Delta G^\circ > 0$, $K < 1$ → Correct. ✓ (c) $\Delta G^\circ = 0$, $K = 1$ → Correct ($\ln 1 = 0$). ✓ (d) $\Delta G^\circ < 0$, $K < 1$ → Incorrect. If $\Delta G^\circ < 0$, then $K > 1$, not $< 1$. ✗

⚠️ Many students get (a) and (d) confused because both involve $\Delta G^\circ < 0$. The rule is simple: negative $\Delta G^\circ$ always means $K > 1$.

$\boxed{\text{Answer: (d)}}$