Entropy order for solid, liquid and gas is : ‌ Gas ‌>‌ Liquid ‌>‌ Solid ‌ (a) H(g)+H(g)→H2(g) Two gaseous atoms combine to form one gaseous molecule. Hence, entropy decreases. (b) H2O(l)→H2O(s) Entropy decreases when liquid freezes to solid form. (c) H2O(l)→H2O(g) Conversion of liquid to gas increases the entropy. (d) A(g)+B(g)+C(s)→2D(s) In the above reaction, the product formed is a solid. Thus, entropy will decreases. So, option (c) is the correct option.