Question

Benzene and naphthalene form an ideal solution at room temperature. For this process, the true statements are:
(i) $\Delta G$ is positive (ii) $\Delta S_{system}$ is positive
(iii) $\Delta S_{surroundings}=0$ (iv) $\Delta H=0$

• A. (ii) and (iv) only
• B. (i) and (iii) only
• C. (ii), (iii) and (iv) only
• D. all of these

Answer 1

Answer: (C)

(ii), (iii) and (iv) only

For an ideal solution with spontaneous process, according to Raoult's law, for an ideal solution

$\Delta H=0$

$\Delta V_{mix}=0$

Since there is no exchange of the heat energy between system and surroundings

$\Delta S_{surroundings}=0$

Thus $\Delta S_{sys}=+ve$

Now, from the relation

$\Delta G=\Delta H–T\Delta S$

$\Delta G$ will be –ve.

So, ii, iii and iv are correct.

The correct option is C.