Almost certainly the ones on the left side of the arrow (or on the bottom of the equilibrium constant expression). However, since you neglected to supply "this chemical reaction", we can't give you a better answer than that.
The substances you have at the beginning of a chemical reaction are the reactants or the reagents.
Reactants
Reactants are added into the equation to form the chemical reaction. Reactants are substances that are changed into products. Without these reactants, there would be no formula, resulting in no product.
The substances you have at the beginning of a chemical reaction are called the reactants.
Endothermic reactions favor the reactants in a chemical reaction.
The substances you have at the beginning of a chemical reaction are the reactants or the reagents.
The reactants
Reactants
The starting materials in a chemical reaction are called reactants.
Reactants are added into the equation to form the chemical reaction. Reactants are substances that are changed into products. Without these reactants, there would be no formula, resulting in no product.
The substances you have at the beginning of a chemical reaction are called the reactants.
Endothermic reactions favor the reactants in a chemical reaction.
The beginning compounds of a chemical reaction are called reactants. Reactants are the substances that react with each other to form products during a chemical reaction.
Reactants are the substances that participate in a chemical reaction and transform into products. They are the starting materials that are used up during the reaction, leading to the formation of new substances.
Reactants are substances that can combine in a chemical reaction.
The starting molecules of a chemical reaction are called "reactants." These reactants undergo a chemical transformation to produce new substances called "products" as a result of the reaction.
In a chemical reaction reactants are transformed in products.