Balance this equation.
_Mg +_Cl2 -->_MgCl2

1Mg + 1Cl2 = 1MgCl2

Explanation:

Hi! When balancing an equation, you want to make sure that there are equal amounts of each element on both sides. When looking at the equation that you provided in the question, look and count how many of each element are on each side. I can see that there is 1 Mg ion on the left and 1 Mg ion on the right. There are also 2 Cl ions on the left and 2 Cl ions on the right. Because they are already equal, the coefficients in front of each compound will be 1. If the amounts were different on each side, that is when you would need to add different coefficients.

Hope this helps! Let me know if you have any other questions about this!