which hydroxide compound yields the lowest concentration of hydroxide ions in aqueous solution? 10pts best ans?

The hydroxide ion concentration depends on the solubility of the solute.

Of the 4 salts listed, Magnesium hydroxide is the least soluble so will give the lowest hydroxide ion concentration:

Magnesium hydroxide is not very soluble in water:

Solubility product (Ksp) of 1.5x10^-11

Calcium hydroxide has higher solubility in water:

Solubility product (Ksp) of 8×10^–6

Both sodium hydroxide and potassium hydroxide are freely soluble in water.

Magnesium Hydroxide has a Ksp of 5.61X10^-12 and Calcium Hydroxide has a Ksp of 5.02x10^-6. Mg(OH)2 has a smaller Ksp so less will dissolve in an aqueous solution, leading to a smaller OH concentration.

Magnesium hydroxide

Magnesium hydroxide...it is only partially soluble in water and will not completely dissociate.

D Mg(OH)2 because it is NOT a strong base and will therefore not completely dissociate in water.