At $$310 \mathrm{~K}$$, the solubility of $$\mathrm{CaF}_{2}$$ in water is $$2.34 \times 10^{-3} \mathrm{~g} / 100 \mathrm{~mL}$$. The solubility product of $$\mathrm{CaF}_{2}$$ is ____________ $$\times 10^{-8}(\mathrm{~mol} / \mathrm{L})^{3}$$. (Give molar mass : $$\mathrm{CaF}_{2}=78 \mathrm{~g} \mathrm{~mol}^{-1}$$)

In the titration of $$\mathrm{KMnO}_{4}$$ and oxalic acid in acidic medium, the change in oxidation number of carbon at the end point is ___________.

The solubility product of a sparingly soluble salt A₂X₃ 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 m² mol^$$-$$1. The value of x is ___________.

pH value of 0.001 M NaOH solution is ____________.