<u>Answer:</u>
<u>For 1:</u> The solubility of magnesium hydroxide at 25°C is 
<u>For 2:</u> The concentration of hydroxide ion in the saturated solution at 25°C is 
<u>Explanation:</u>
The equation for the ionization of the magnesium hydroxide is given as:

s 2s
Expression for the solubility product of
will be:
![K_{sp}=[Mg^{2+}][OH^-]^2\\\\K_{sp}=s\times (2s)^2=4s^3](https://tex.z-dn.net/?f=K_%7Bsp%7D%3D%5BMg%5E%7B2%2B%7D%5D%5BOH%5E-%5D%5E2%5C%5C%5C%5CK_%7Bsp%7D%3Ds%5Ctimes%20%282s%29%5E2%3D4s%5E3)
We are given:

Putting values in above equation, we get:

Hence, the solubility of magnesium hydroxide at 25°C is 
Concentration of hydroxide ion in the solution = 2s = 
Hence, the concentration of hydroxide ion in the saturated solution at 25°C is 