When $100 \ mL$ of $0.1 \ M$ $NaCN$ solution is titrated with $0.1 \ M$ $HCl$ solution,the variation of $pH$ of the solution with the volume of $HCl$ added will be:

The species present in solution when $CO_2$ is dissolved in water are

How much heat is evolved when $100 \, mL$ of $0.1 \, N \, H_2SO_4$ is mixed with $150 \, mL$ of $0.1 \, N \, NaOH$?

What will be the change in acidity if
$(i)$ $CuSO_4$ is added in saturated $(NH_4)_2SO_4$ solution
$(ii)$ $SbF_5$ is added in anhydrous $HF$?

The dissociation constant of a certain weak acid is $1.0 \times 10^{-4}$. What is the equilibrium constant for its reaction with a strong base?

At $25^{\circ}C$, $20.0 \ mL$ of $0.2 \ M$ weak monoprotic acid $HX$ is titrated against $0.2 \ M$ $NaOH$. The $pH$ of the solution $(a)$ at the start of the titration (when $NaOH$ has not been added) and $(b)$ when $10 \ mL$ of $NaOH$ is added respectively, are:
Given: $K_a = 5 \times 10^{-4}, pK_a = 3.3, \alpha << 1$