Which phrase describes a feature of groundwater? -feeds rivers
--provides habitats
-makes up 75% of fresh water
--used for hydroelectric power

number 1

Explanation:

Groundwater mainly contributes the water into the surface water like streams, rivers, and lakes.

Explanation:

For a balanced equation, the number of molecules of all the elements or ions in the reactants and products must be equal.

In the reaction involving the formation of from Mg and , 3 molecules of Mg should react with 1 molecule of . Thus, the balanced equation is written as;