When $300 \, mL$ of $M/3 \, HCl$,$200 \, mL$ of $M/2 \, HNO_3$,and $400 \, mL$ of $M/4 \, NaOH$ are mixed,and the total volume is made up to $1 \, dm^3$,what will be the $pH$ of the resulting solution?

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.

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 $9.0 \ S \ cm^2 \ mol^{-1}$?

The pairs of compounds which cannot exist together in aqueous solution are :
$I. NaH_2PO_4$ and $Na_2CO_3$ $II. Na_2CO_3$ and $NaHCO_3$
$III. NaOH$ and $NaH_2PO_4$ $IV. NaHCO_3$ and $NaOH$

In which of the following mixed aqueous solutions, $pH = pK_{a}$ at equilibrium?
$(1)$ $100 \ mL$ of $0.1 \ M \ CH_{3}COOH + 100 \ mL$ of $0.1 \ M \ CH_{3}COONa$
$(2)$ $100 \ mL$ of $0.1 \ M \ CH_{3}COOH + 50 \ mL$ of $0.1 \ M \ NaOH$
$(3)$ $100 \ mL$ of $0.1 \ M \ CH_{3}COOH + 100 \ mL$ of $0.1 \ M \ NaOH$
$(4)$ $100 \ mL$ of $0.1 \ M \ CH_{3}COOH + 100 \ mL$ of $0.1 \ M \ NH_{3}$

If $10\%$ of a $5 \times 10^{-3} \, M \, H_2CO_3$ solution dissociates,then the concentration of $H^{+}$ ions is equal to $......$.