$CrO_4^{2-}$ (Yellow) changes to $Cr_2O_7^{2-}$ (orange) in $pH = x$ and vice versa in $pH = y$,hence $x$ and $y$ are respectively

Which one of the following statements is not true?

The solubility product of a sparingly soluble salt $A_{2}X_{3}$ is $1.1 \times 10^{-23}$. If specific conductance of the solution is $3 \times 10^{-5} \ S \ m^{-1}$,the limiting molar conductivity of the solution is $x \times 10^{-3} \ S \ m^{2} \ mol^{-1}$. The value of $x$ is ...

Which of the following statement(s) is(are) correct?

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 dissociation constants for acetic acid and $HCN$ at $25\,^{\circ}C$ are $1.5 \times 10^{-5}$ and $4.5 \times 10^{-10}$ respectively. The equilibrium constant for the equilibrium $CN^{-} + CH_3COOH \rightleftharpoons HCN + CH_3COO^{-}$ would be