ANSWER
Mg(OH)2 is a base
STEP-BY-STEP EXPLANATION:
Firstly, we need to define the word "acid and base"
An acid is a substance that will produce hydrogen ion as the only positive ion when dissolved in water
WHILE
A base is a substance that can neutralize the acid by reacting with hydrogen ions to produce salt and water. A base also contain hydroxyl ion (OH)
From the above definition, you will see that Mg(OH)2 is a base
