Question

Which among the following statements is / are correct?

• A. pH of ${10}^{-8}$ M HCl is equal to 8
• B. Conjugate base of $H_{2}P{O}_4^{-}$ IS $HP{O}_4^{-2}$
• C. pH of 0.1M NaCl (aqueous solution)$=\frac{1}{2}P{K}_w$
• D. Ionization of water increases with decrease in temperature

Answer 1

Answer: (B), (C)

Conjugate base of $H_{2}P{O}_4^{-}$ IS $HP{O}_4^{-2}$
pH of 0.1M NaCl (aqueous solution)$=\frac{1}{2}P{K}_w$

$H_{2}P{O}_4^{-}⟶HP{O}_4^{-2}+H^{+}$

Hence, $HP{O}_4^{-2}$ is a conjugate base of $H_{2}P{O}_4^{-}$
Also NaCl is neutral so its $pH$ is 7 and $p{K}_w$ is 14.

pH of HCl cannot be equal to 8 because it is strong acid its pH will be less than 7.

And ionization of water increases with increase in temperature.