Acombination reaction is when two or more combine to form one product. a decomposition reaction is when a substance breaks down into two or more simpler substances in a chemical reaction.

Reactants

Explanation:

A combination reaction is usually defined as a type of chemical reaction in which two or more reactants are fused together to form a single product. For example, The two elements Hydrogen and Chlorine are linked together to form Hydrochloric acid.

This can be written as,

H + Cl > HCl (acid)

A decomposition reaction is usually defined as a type of chemical reaction in which a single and complex substance is disintegrated into two or more simple substances. For example, the same above reaction can be disintegrated into-

HCl (acid) > H + Cl

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