Which of the following processes entropy change $(\Delta S)$ is negative?

I. Sublimation of dry ice

II. Freezing of water

III. Crystallisation of the dissolved substance

IV. Burning of rocket fuel

At $25^{\circ} \mathrm{C}$, the percentage of ionisation of ' $x$ ' M acetic acid is 4.242 . What is the value of $x$ ? $\left(K_{\mathrm{a}}=1.8 \times 10^{-5}\right)$

At $T(\mathrm{~K}), K_C$ value for

$\mathrm{AO}_2(\mathrm{~g})+\mathrm{BO}_2(\mathrm{~g}) \rightleftharpoons \mathrm{AO}_3(\mathrm{~g})+\mathrm{BO}(\mathrm{g})$ is 16 . In a closed 1 L flask, one mole each of $A \mathrm{O}_2, B \mathrm{O}_2, A \mathrm{O}_3$ and $B \mathrm{O}$ are taken and heated to $T(\mathrm{~K})$.

What is the concentration (in $\mathrm{mol} \mathrm{L}^{-1}$ ) of $\mathrm{AO}_3$ at equilibrium?

The incorrect statement in the following is