Which among the following salt solution in water is acidic in nature?

What is the molar concentration of acetic acid if value of it's, dissociation constant is $$1.8 \times 10^{-5}$$ and degree of dissociation is 0.02 ?

A buffer solution is prepared by mixing equimolar acetic acid and sodium acetate. If '$$\mathrm{K}_d$$' of acetic acid is $$1.78 \times 10^{-5}$$, find the $$\mathrm{pH}$$ of buffer solution.

The solubility product of $$\mathrm{Mg}(\mathrm{OH})_2$$ is $$1.8 \times 10^{-11}$$ at $$298 \mathrm{~K}$$. What is its solubility in $$\mathrm{mol} \mathrm{~dm}^{-3}$$ ?