. Mg(s) + 2 H+(aq) – Mg2+(aq) + H2(g)
An experiment is done to find the volume of H2(g)
that is formed when a certain mass of Mg(s) reacts
with excess hydrochloric acid. The net ionic
equation for this reaction is shown. The experiment
is run with a 0.042-gram sample of pure Mg(s) and a
solution of 2.0 M hydrochloric acid.
Calculate the number of moles of Mg in the 0.0420 g sample.

answer:

the reaction is type of combination reaction.

explanation:

on the product side, there are 2 molecules of bonded to fe   which means one atom of fe are combined two molecules of . so, balanced chemical equation becomes :

this reaction follows the reaction type of combination reaction. a combination reaction is defined as chemical reaction in which reactants combines together to form a single product.