Question

explain the term reactant and product giving examples

Answer 1

reactants are the elements which react together to produce a product for e.g.
Mg + O2 --- → MgO

Answer 2

The substances that result from this recombination of atoms are called theproducts of the reaction. When chemical reactions are written down, the reactants are written on the left side, in a similar manner to a math equation; one reactant plus another.
C + O2 gives CO2

C and O2 are the reactants
CO2 is the product