The first and second ionization constants of a weak dibasic acid $H_{2}A$ are $8.1 \times 10^{-8}$ and $1.0 \times 10^{-13}$ respectively. $0.1 \text{ mol}$ of $H_{2}A$ was dissolved in $1 \text{ L}$ of $0.1 \text{ M}$ $HCl$ solution. The concentration of $HA^{-}$ in the resultant solution is:

Calculate the $pH$ of a mixed solution containing $10 \ mL$ of $0.2 \ M$ $Ca(OH)_2$ and $25 \ mL$ of $0.1 \ M$ $HCl$.

Calculate the ionic product of the solution formed by mixing equal volumes of $0.004 \, M \, CaSO_4$ and $0.002 \, M \, H_2SO_4$.

Assign $A$,$B$,$C$,$D$ from the given type of reaction.
$2NaOH + Zn(OH)_2 \rightarrow Na_2ZnO_2 + 2H_2O$

What is the percent dissociation of $NH_4OH$ if the molar conductance at zero concentration for $NH_4Cl, NaCl$,and $NaOH$ are $130, 109$,and $213 \ S \ cm^2 \ mol^{-1}$ respectively,and the molar conductivity of $0.01 \ M \ NH_4OH$ is $9.0 \ S \ cm^2 \ mol^{-1}$?

$1 \times 10^{-5} \ S \ M$ $AgNO_3$ is added to $1 \ L$ of a saturated solution of $AgBr$. The conductivity of this solution at $298 \ K$ is $......... \times 10^{-8} \ S \ m^{-1}$.
Given: $K_{sp}(AgBr) = 4.9 \times 10^{-13}$ at $298 \ K$,$\lambda^0_{Ag^{+}} = 6 \times 10^{-3} \ S \ m^2 \ mol^{-1}$,$\lambda^0_{Br^{-}} = 8 \times 10^{-3} \ S \ m^2 \ mol^{-1}$,$\lambda^0_{NO_3^-} = 7 \times 10^{-3} \ S \ m^2 \ mol^{-1}$.