Question

In which of the following processes does entropy increase?
(a) $B{r}_2\left(l\right)⟶B{r}_2\left(g\right)$
(b) $H_{2}O\left(s\right)⟶H_{2}O\left(g\right)$
(c) $N_2(1atm,{100}^{\circ }C)⟶N_2(1atm,{150}^{\circ }C)$
(d) $N_2\left(g\right)+3H_2\left(g\right)⟶2N{H}_3\left(g\right)$
(e) $CaC{O}_3\left(s\right)⟶CaO\left(s\right)+C{O}_2\left(g\right)$

• A. a, b, c, d, e
• B. Only a, b, c, e
• C. Only a, b, e
• D. Only a, b, d, e

Answer 1

The correct option is B Only a, b, c, e

Entropy is a measure of randomness. So,
(a) Here physical state of $Br$ is changes from liquid to gas. So, entropy increases in this process.
b) Similary, the physical state of $H_{2}O$ changes from solid to liquid. So, entropy increases in this process.
(c) Here we are increasing the temperature, hence entropy increases.
d) In this reaction 2 moles of $N_2$ and 3 moles of $H_2$ react to give two moles of $N{H}_3$, thus entropy will decrease.
e) $CaC{O}_3$ decomposes. So, entropy will increase.