keq

14. N2(g) + 3H2(g) ⇌ 2NH3(g) ; ΔH° = -92.22 kJ•mol-1 Which change would decrease the Keq in the above reaction? Options: A. Adding an iron catalyst. B. Decreasing the volume of the vessel. C. Injecting H2 gas. D. Cooling ammonia gas into a liquid. E. Increasing the temperature. I...

What is the relationship between Keq and Ka? I don't understand why A is the answer to this question. Thanks in advance!