For the reaction H2 (g) + I2(g)⇌2HI(g),Koc= 66.9 at 350∘C and Koc= 50.0 at 448 ∘C. The reaction has
ΔH = +ve.
ΔH = -ve.
ΔH = Zero
ΔH whose sign cannot be predicted
Since Kc decreases with increase in temperature, the reaction must be exothermic. Hence ΔH = -ve.