Mg(OH)2 + HNO3 → Mg(NO3)2 + H2O

To balance this equation, we need to make sure that the number of atoms of each element is the same on both sides of the equation.

1. First, we balance the magnesium (Mg) atoms. There is one Mg atom on the left side and one Mg atom on the right side, so this is already balanced.

2. Next, we balance the oxygen (O) atoms. There are two O atoms on the left side from Mg(OH)2 and three O atoms on the right side from Mg(NO3)2 and H2O. To balance this, we can add a coefficient of 2 in front of H2O:

Mg(OH)2 + HNO3 → Mg(NO3)2 + 2H2O

Now we have four O atoms on both sides of the equation.

3. We then balance the nitrogen (N) atoms. There is one N atom on the left side from HNO3 and two N atoms on the right side from Mg(NO3)2. To balance this, we can add a coefficient of 2 in front of HNO3:

Mg(OH)2 + 2HNO3 → Mg(NO3)2 + 2H2O

Now we have two N atoms on both sides of the equation.

4. Finally, we balance the hydrogen (H) atoms. There are two H atoms on the left side from Mg(OH)2 and four H atoms on the right side from 2H2O. To balance this, we can add a coefficient of 2 in front of HNO3:

Mg(OH)2 + 2HNO3 → Mg(NO3)2 + 2H2O

Now we have four H atoms on both sides of the equation.

The balanced chemical equation is:

Mg(OH)2 + 2HNO3 → Mg(NO3)2 + 2H2O