Which is/are correct statements?

(i) When $100 \mathrm{mL}$ of $0.1 \mathrm{M} \mathrm{NaCN}$solution is titrated with $0.1 \mathrm{M} \mathrm{HCl}$ solution, the variation of $\mathrm{pH}$ of the solution with the volume of $\mathrm{HCl}$ added will be (as shown in the figure):

(ii) The variation of the degree of dissociation $\alpha$, with the concentration for a weak electrolyte at a particular temperature is best represented by (as shown in the figure).

(iii) $0.1 \mathrm{M}$ acetic acid solution is titrated against $0.1 \mathrm{M} \mathrm{NaOH}$ solution. The difference in $\mathrm{pH}$ between $1/4$ and $3/4$ stages of neutralization of acid will be $2\times \log 3$.

A weak acid (or base) is titrated against a strong base (or acid) and the volume V of a strong base (or acid) is plotted against the $\mathrm{pH}$ of the solution (as shown in figure). The weak electrolyte (i.e. acid or base) could be:

Titration curves for $0.1 \mathrm{M}$ solutions of three weak acids $\mathrm{HA},{\mathrm{HA}}_2$ and ${\mathrm{HA}}_3$ with ionization constants ${\mathrm{K}}_1,{\mathrm{K}}_2$and ${\mathrm{K}}_3$ respectively are plotted as shown in the figure. Which of the following is/are true?

Titration curves for $0.1 \mathrm{M}$ solutions of three weak acids $\mathrm{HX},\mathrm{HY}$ and $\mathrm{HZ}$ with ionization constants ${\mathrm{K}}_1,{\mathrm{K}}_2$ and ${\mathrm{K}}_3$, respectively as shown in figure below. The volume of $\mathrm{NaOH}$  added is in $\mathrm{mL}.$