Complete the following reaction:

Magnesium + hydrochloric acid → magnesium chloride + ______

Acids react to most metals and salt is produced. But unlike the reaction along with acids and bases, we don't get any water. Instead, we get hydrogen gas. This is the general equation for such reactions: 

metal + acid → salt + hydrogen.

So, the reaction is,

magnesium + hydrochloric acid → magnesium chloride + hydrogen