The $pH$ of the solution formed by mixing $5 \ mL$ of $M/5$ $HCl$ and $10 \ mL$ of $M/10$ $NaOH$ is:

If the equilibrium constant of $CH_3COOH + H_2O \rightleftharpoons CH_3COO^{-} + H_3O^{+}$ is $1.8 \times 10^{-5}$,what is the equilibrium constant for the reaction $CH_3COOH + OH^{-} \rightleftharpoons CH_3COO^{-} + H_2O$?

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

$1 \times 10^{-5} \ S \ M$ $AgNO_3$ 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 $298 \ K$,$\lambda^0_{Ag^{+}} = 6 \times 10^{-3} \ S \ m^2 \ mol^{-1}$,$\lambda^0_{Br^{-}} = 8 \times 10^{-3} \ S \ m^2 \ mol^{-1}$,$\lambda^0_{NO_3^-} = 7 \times 10^{-3} \ S \ m^2 \ mol^{-1}$.

The plot of $pH$-metric titration of weak base $NH_4OH$ vs strong acid $HCl$ looks like:

When a standard solution of $NaOH$ is left in the air for a few hours,