Consider Mg$($OH$)2$ with ksp$=5\mathrm{.}6\backslash$times $1012$

A$.$ Determine the solubility of Mg$($OH$)2$ in water

B$.$ Determine the solubility of Mg$($OH$)2$ in $0\mathrm{.}40$ mol$/$L of Na$2$CO$3$ solution. ka$=2\mathrm{.}2\backslash$times $104$

C$.$ Explain common ion effect and how it would affect the solubility.