Question

The occurrence of the reaction is impossible if

• A. $\Delta H$ is $+ve;\Delta S$ is also $+ve$
• B. $\Delta H$ is $-ve;\Delta S$ is also $-ve$
• C. $\Delta H$ is $-ve;\Delta S$ is $+ve$
• D. $\Delta H$ is $+ve;\Delta S$ is $-ve$

Answer 1

Answer: (D)

When $\Delta G$ is $+$ ve, then reaction is not possible.
$\Delta G=\Delta H-T.\Delta S$ If $\Delta H=+ve$ and $\Delta S=+ve$, then $\Delta G=+ve$
only when $\Delta H>T.\Delta S$ but if $\Delta H=+ve$ and $\Delta S=-ve$, then $\Delta G=+ve$.