For the reaction, H2(g)+I2(g) ⇌ 2HI(g), the standard free energy is ΔG°>0. The equilibrium constant (KC) would be

∆G0 and K are related as ∆G0 = - RT ln Kc when G0> 0 means ∆G0 is positive. This can be so only if ln KC is negative, i.e. Kc < 1.