Mg + 2 HCl → MgCl₂ + H₂

Represents a single displacement reaction.

Here's why:

* Single Displacement: In this type of reaction, a more reactive element (in this case, magnesium, Mg) displaces a less reactive element (hydrogen, H) from a compound.

* Magnesium (Mg) is more reactive than hydrogen, so it takes the place of hydrogen in the compound, hydrochloric acid (HCl).

* Hydrogen (H) is then released as a gas (H₂).

Let's break down the reaction further:

* Reactants: Magnesium (Mg) and hydrochloric acid (HCl)

* Products: Magnesium chloride (MgCl₂) and hydrogen gas (H₂)

Key features:

* One element replaces another in a compound.

* The products are a new compound and a free element.