The hydrogen ion concentration of a $0.1 \ N$ solution of $CH_3COOH$,which is $30 \%$ dissociated,is (in $M$)

$100 \ cm^3$ of $0.1 \ N \ HCl$ solution is mixed with $100 \ cm^3$ of $0.2 \ N \ NaOH$ solution. The resulting solution is

At $27^{\circ} C$,the degree of dissociation of $HA$ (weak acid) in $0.5 \ M$ of its solution is $1 \%$. The concentrations of $H_3O^{+}$,$A^{-}$,and $HA$ at equilibrium (in $mol \ L^{-1}$) are respectively

The decreasing order of electrical conductivity of the following aqueous solutions is:
$0.1 \ M$ Formic acid $(a)$
$0.1 \ M$ Acetic acid $(b)$
$0.1 \ M$ Benzoic acid $(c)$

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 $H_2PO_4^{-}$ is $HPO_4^{2-}$.
$ (C) $ $K_w$ increases with increase in temperature.
$ (D) $ When a solution of weak monoprotic acid is titrated against a strong base at half neutralisation point,$pH = pK_a$.
Choose the correct answer from the option given below.

The solubility of $AgCl$ is $4 \times 10^{-6} \ M$. Find its $K_{sp}$. Also,find its new solubility in the presence of $2 \times 10^{-3} \ M \ CaCl_2$.