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

Analyzing each statement:

(A) pH of $$1 \times 10^{-8}$$ M HCl is 8: Incorrect. At such low concentration, we must consider the autoionization of water. The pH will be slightly less than 7, not 8 (an acid cannot have pH > 7).

(B) Conjugate base of H₂PO₄⁻ is HPO₄²⁻: Correct. H₂PO₄⁻ donates a proton to become HPO₄²⁻.

(C) K_w increases with increase in temperature: Correct. The dissociation of water is endothermic, so K_w increases with temperature.

(D) At half neutralization point, pH = ½ pKa: Incorrect. At the half neutralization point of a weak acid, pH = pKa (Henderson-Hasselbalch equation: pH = pKa + log(1) = pKa), not ½ pKa.

Correct statements: B and C.

This matches option 1: (B), (C).