The $\mathrm{pH}$ of pure water at $80°\mathrm{C}$ is

Which of the following equations give ionic product of water?

(i) ${\mathrm{NH}}_{3\left(\mathrm{aq}\right)}+{\mathrm{H}}_2\mathrm{O}\leftrightarrows {\mathrm{NH}}_{4\left(\mathrm{aq}\right)}^{+}+{\mathrm{OH}}_{\left(\mathrm{aq}\right)}^{-}$

(ii) ${\mathrm{NH}}_{4\left(\mathrm{aq}\right)}^{+}+{\mathrm{H}}_2\mathrm{O}\leftrightarrows {\mathrm{H}}_3{\mathrm{O}}^{+}+{\mathrm{NH}}_{3\left(\mathrm{aq}\right)}$

(iii) ${\mathrm{NH}}_{2\left(\mathrm{aq}\right)}^{-}+{\mathrm{H}}_2\mathrm{O}\leftrightarrows {\mathrm{NH}}_{3\left(\mathrm{aq}\right)}+{\mathrm{OH}}^{-}$

(iv) ${\mathrm{NH}}_{3\left(\mathrm{aq}\right)}+{\mathrm{OH}}_{\left(\mathrm{aq}\right)}^{-}\leftrightarrows {\mathrm{NH}}_{2\left(\mathrm{aq}\right)}^{-}+{\mathrm{H}}_2\mathrm{O}$

At $90°\mathrm{C}$, pure water has $\left[{\mathrm{H}}_3{\mathrm{O}}^{+}\right] = {10}^{-6} \mathrm{mol} {\mathrm{L}}^{-1}$. What is the value of ${\mathrm{K}}_{\mathrm{\omega }}$ at $90°\mathrm{C}$?

Which is/are correct statements?

(i) In any strong acid solution, the concentration of $\left[{\mathrm{OH}}^{-}\right]$ will be zero.
(ii) If $∆{\mathrm{G}}^{\mathrm{o}}$ of a reaction is positive, then the reaction will not proceed at all, in the directions of reactants and products.

(iii) Titration curves are drawn for (about the figure shown).

      (a) $1\mathrm{M} \mathrm{HCl} (50 \mathrm{mL})$ with $1\mathrm{M} \mathrm{NaOH}$ and

       (b) $0.01\mathrm{M} \mathrm{HCl} (50 \mathrm{mL}\mathrm{)}$with $0.01\mathrm{M} \mathrm{NaOH}$ on the same graph paper they look like:

Which of the following is incorrect for pure water at the given temperature?

(At the given temperature ${\mathrm{K}}_{\mathrm{w}}$ for water is  $4\mathrm{ }\times \mathrm{ }{10}^{–14}$)