Question

Which of the following statements is/are correct?
a) In the decomposition of an oxide into oxygen and metal vapour, entropy increases.
b) Decomposition of an oxide is an endothermic change.
c) To make $\Delta G^0$ negative, temperature should be high enough so that $T\Delta S^0>\Delta H^0$.

• A. (a), (b) only are correct
• B. (b), (c) only are correct
• C. (a), (c) only are correct
• D. (a), (b), (c) are correct

Answer 1

Answer: (D)

(a), (b), (c) are correct

Decomposition of metal oxide:

$M{O}_2\to M+O_2$

If we compare the reactant and product, we see that the number of products are more. Also among the product side even at room temperature, one product is gas so in this process randomness increases, i.e., entropy increases.
This is an endothermic reaction.

So, to increase free energy change, the temperature should be increased to make $T\Delta S^o>\Delta H^o$.
Hence option D is correct.