Which of the following statement(s) is/are correct? (A) The pH of $1 \times 10^{-8} \mathrm{M} \mathrm{HCl}$ solution is 8 . (B) The conjugate base $\mathrm{H}_2 \mathrm{PO}_4^{-}$is $\mathrm{HPO}_4^{2-}$. (C) $\mathrm{K}_{\mathrm{w}}$ increases with increase in temperature. (D) When a solution of weak monoprotic acid is titrated against a strong base at half neutralisation point, $\mathrm{pH}=\frac{1}{2} \mathrm{pK}_{\mathrm{a}}$ Choose the correct answer from the option given below.