What is the concentration of $[OH^-]$ in a mixture of $20 \ mL$ of $0.050 \ M \ HCl$ and $30 \ mL$ of $0.10 \ M \ Ba(OH)_2$ (in $M$)?

When $10 \ mL$ of $0.1 \ M$ acetic acid $(pK_a = 5.0)$ is titrated with $10 \ mL$ of $0.1 \ M$ ammonia $(pK_b = 5.0)$,at what $pH$ will the equivalence point be reached?

For a concentrated solution of a weak electrolyte ($K_{eq} = $ equilibrium constant) $A_2B_3$ of concentration '$c$',the degree of dissociation '$\alpha$' is

Identify the correct statements from the following.
$(A)$ The ionic product of water at $100^{\circ} C$ is $< 10^{-14}$.
$(B)$ $pH$ of a solution decreases with increasing temperature.
$(C)$ $NaH_2PO_4$ on hydrolysis gives a basic solution.
$(D)$ $NH_3$ can act both as Bronsted acid and base.

The molar conductivity of $0.01 \text{ M}$ monobasic acid at $25 \text{ }^\circ\text{C}$ is $15 \text{ ohm}^{-1} \text{cm}^2 \text{mol}^{-1}$. The molar conductivity of the same acid at infinite dilution is $375 \text{ ohm}^{-1} \text{cm}^2 \text{mol}^{-1}$. Calculate $[H^+]$ in solution.

When $100 \ mL$ of $1.0 \ M \ HCl$ was mixed with $100 \ mL$ of $1.0 \ M \ NaOH$ in an insulated beaker at constant pressure,a temperature increase of $5.7^{\circ} C$ was measured for the beaker and its contents (Expt. $1$). Because the enthalpy of neutralization of a strong acid with a strong base is a constant $\left(-57.0 \ kJ \ mol ^{-1}\right)$,this experiment could be used to measure the calorimeter constant. In a second experiment (Expt. $2$),$100 \ mL$ of $2.0 \ M$ acetic acid $\left(K_a=2.0 \times 10^{-5}\right)$ was mixed with $100 \ mL$ of $1.0 \ M \ NaOH$ (under identical conditions to Expt. $1$) where a temperature rise of $5.6^{\circ} C$ was measured.
(Consider heat capacity of all solutions as $4.2 \ J \ g ^{-1} K ^{-1}$ and density of all solutions as $1.0 \ g \ mL ^{-1}$)
$1.$ Enthalpy of dissociation (in $kJ \ mol ^{-1}$) of acetic acid obtained from the Expt. $2$ is
$(A) \ 1.0 \ (B) \ 10.0 \ (C) \ 24.5 \ (D) \ 51.4$
$2.$ The $pH$ of the solution after Expt. $2$ is
$(A) \ 2.8 \ (B) \ 4.7 \ (C) \ 5.0 \ (D) \ 7.0$
Give the answer for question $1$ and $2.$