A solution is $0.10\mathrm{M}$ in $\mathrm{CH}{}_3\mathrm{COOH}$ and $0.10\mathrm{M}$ in $\mathrm{CH}{}_3\mathrm{COONa}$ ($\mathrm{p}{K}_a=4.74$). Assume volume changes on adding solids or gas are negligible. Select the correct statement(s).

1. AThe pH of the solution is 4.74
2. BAfter adding $0.010\mathrm{mol}$ of solid $\mathrm{NaOH}$ per litre, the pH becomes 4.83
3. COn diluting tenfold with water, the pH rises to 5.74
4. DAfter adding $0.10\mathrm{mol}$ of $\mathrm{HCl}$ per litre, the pH is 4.74