MCQ
In which case change in entropy is negative ?
- AEvaporation of water
- BExpansion of a gas at constant temperature
- CSublimation of solid to gas
- ✓$2H(g)\rightarrow H_2(g)$
Due to bond formation, entropy decreases
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

$2 \mathrm{~A}_{(\mathrm{g})}+\mathrm{B}_{(\mathrm{g})} \rightarrow \mathrm{C}_{(\mathrm{g})}$
The initial rate of the reaction is recorded as $r_1$ when the reaction starts with $1.5 \mathrm{~atm}$ pressure of $\mathrm{A}$ and $0.7 \mathrm{~atm}$ pressure of B. After some time, the rate $r_2$ is recorded when the pressure of $C$ becomes $0.5 \mathrm{~atm}$. The ratio $r_1: r_2$ is $\qquad$ $\times 10^{-1}$.
(Nearest integer)