At $25 \, ^\circ C$,the dissociation constant of pure water is equal to .......

$A$ $20 \ mL$ sample of a $0.1 \ M$ solution of the weak monoprotic acid $HA$ is titrated with $0.25 \ M \ NaOH$. The volume of $NaOH$ solution required to reach the equivalence point is: ............. $mL$

$K_a$ for $CH_3COOH$ is $1.9 \times 10^{-5}$. Calculate the $pH$ at the equivalence point in the titration of $0.1 \ M$ $CH_3COOH$ with $0.1 \ M$ $NaOH$.

Two solutions $A$ and $B$,each of $100 \; L$,were made by dissolving $4 \; g$ of $NaOH$ and $9.8 \; g$ of $H_{2}SO_{4}$ in water,respectively. The $pH$ of the resultant solution obtained by mixing $40 \; L$ of solution $A$ and $10 \; L$ of solution $B$ is:

At $25^{\circ} C$, the molar conductance of $0.007 \ M$ hydrofluoric acid is $150 \ \text{mho} \ cm^{2} \ mol^{-1}$ and its $\Lambda_{m}^{\circ} = 500 \ \text{mho} \ cm^{2} \ mol^{-1}$. The value of the dissociation constant of the acid at the given concentration at $25^{\circ} C$ is

The $pH$ at which the maximum hydrate is present in a solution of oxaloacetic acid $(HOOC-CO-CH_2-COOH)$ with $pK_{a1} = 2.2$ and $pK_{a2} = 3.98$ is: