The correct option is B 1(Kc)2
The given reaction is,
12H2(g)+12I2(g)⇌HI(g) ....eqn(i)
Hence, Kc=[HI][H2]1/2[I2]1/2 .....eqn(ii)
Now, reverse the eqn(i) and multiply by 2, we get
2HI(g)⇌H2(g)+I2(g)
Hence, K′c=[H2][I2][HI]2 .....eqn(iii)
Equating equation (ii) and (iii), we get
K′c=1(Kc)2