Which of the following statement$(s)$ is/are correct.
$A$. The $pH$ of $1 \times 10^{-8} \ M$ aqueous solution of $HCl$ is $8$
$B$. The conjugate base of $H_2PO_4^{\ominus}$ 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,then at the half-neutralization point,$pH = pK_a$.

Blue litmus turns red in the following mixture of acid and base:

When $200 \ mL$ solution of $HCl$ of $pH=2$ is mixed with $300 \ mL$ solution of $NaOH$ of $pH=12$,the $pH$ of resulting solution is $(\log 2=0.3)$

$A$ soft drink was bottled with a partial pressure of $CO_2$ of $3 \ bar$ over the liquid at room temperature. The partial pressure of $CO_2$ over the solution approaches a value of $30 \ bar$ when $44 \ g$ of $CO_2$ is dissolved in $1 \ kg$ of water at room temperature. The approximate $pH$ of the soft drink is............... $\times 10^{-1}$ (First dissociation constant of $H_2CO_3 = 4.0 \times 10^{-7}$; $\log 2 = 0.3$; density of the soft drink $= 1 \ g \ mL^{-1}$)

How much heat will be evolved when $500 \, mL$ of $0.2 \, N \, H_2SO_4$ is mixed with $50 \, mL$ of $1 \, N \, KOH$?

Formic acid $(HCOOH)$ is a weak acid and hydrochloric acid $(HCl)$ is a strong acid. It follows that the: