Consider the following electrochemical cell :

$$ \mathrm{Pt}\left|\mathrm{O}_2(\mathrm{~g})(1 \mathrm{bar})\right| \mathrm{HCl}(\mathrm{aq}) \| \mathrm{M}^{2+}(\mathrm{aq}, 1.0 \mathrm{M}) \mid \mathrm{M}(\mathrm{~s}) $$

The pH above which, oxygen gas would start to evolve at anode is $\_\_\_\_$ (nearest integer).

$$ \left.\left[\begin{array}{ll} \text { Given : } & \mathrm{E}_{\mathrm{M}^{2+} / \mathrm{M}}^{\mathrm{o}}=0.994 \mathrm{~V} \\ & \mathrm{E}_{\mathrm{O}_2 / \mathrm{H}_2 \mathrm{O}}^{\mathrm{o}}=1.23 \mathrm{~V} \end{array}\right\} \text { standard reduction potential } \\ \text {and} \frac{\mathrm{RT}}{\mathrm{F}}(2.303)=0.059 \mathrm{~V} \text {at the given condition}\right] $$

The mass of benzanilide obtained from the benzoylation reaction of 5.8 g of aniline, if yield of product is $82 \%$, is $\_\_\_\_$ g (nearest integer).

(Given molar mass in $\mathrm{g} \mathrm{mol}^{-1} \mathrm{H}: 1, \mathrm{C}: 12, \mathrm{~N}: 14, \mathrm{O}: 16$ )

Among the following oxides of $3 d$ elements, the number of mixed oxides are $\_\_\_\_$ .

$$ \mathrm{Ti}_2 \mathrm{O}_3, \mathrm{~V}_2 \mathrm{O}_4, \mathrm{Cr}_2 \mathrm{O}_3, \mathrm{Mn}_3 \mathrm{O}_4, \mathrm{Fe}_3 \mathrm{O}_4, \mathrm{Fe}_2 \mathrm{O}_3, \mathrm{Co}_3 \mathrm{O}_4 $$

If the enthalpy of sublimation of Li is $155 \mathrm{~kJ} \mathrm{~mol}^{-1}$, enthalpy of dissociation of $\mathrm{F}_2$ is $150 \mathrm{~kJ} \mathrm{~mol}^{-1}$, ionization enthalpy of Li is $520 \mathrm{~kJ} \mathrm{~mol}^{-1}$, electron gain enthalpy of F is $-313 \mathrm{~kJ} \mathrm{~mol}^{-1}$, standard enthalpy of formation of LiF is $-594 \mathrm{~kJ} \mathrm{~mol}^{-1}$. The magnitude of lattice enthalpy of LiF is $\_\_\_\_$ $\mathrm{kJ} \mathrm{mol}^{-1}$. (Nearest Integer)