Question

Will the following reaction occur?

Answer 1

Answer: Yes, magnesium will replace hydrogen because magnesium is higher on the activity  series list.

Explanation:

A single replacement reaction is one in which a more reactive element displaces a less reactive element from its salt solution.  

A general single displacement reaction can be represented as :

$X+YZ\rightarrow XZ+Y$

$Mg+2HCl\rightarrow MgCl_2+H_2$

When magnesium is added to hydrochloric acid, magnesium being more reactive than hydrogen displaces hydrogen atom its salt solution and lead to formation of magnesium chloride and hydrogen gas.