If the equilibrium constants for the systems H2 + I2 <═> 2HI and 2HI <═> H2 + I2 are K1 and K2 respectively, the relationship between K1 and K2 is:

If the equilibrium constants for the systems H₂ + I₂ <═>  2HI and 2HI <═> H₂ + I₂ are K1 and K2 respectively, the relationship between K1 and K2 is:

K1 = k2      

K1 = 2K2             

K1 = K2/2 

K1 = 1/ K2