Answer :
and
pair of substances are the products.
Explanation :
The given balanced chemical reaction is,

Balanced chemical reaction is the reaction in which the number of atoms of an individual elements present on reactant side must be equal to the product side.
The species present on the left side of the right arrow is the reactant and the species present on the right side of the right arrow is the product.
In the given balanced reaction,
and
are reactants.
and
are products.
Hence,
and
pair of substances are the products.