Why are decomposition reactions called the opposite of combination reactions? Write equations for these reactions.
Answer
| COMBINATION REACTION | DECOMPOSITION REACTION | 
| Two or more substances react to form a single product in a Combination Reaction . | A single reactant breaks down into more than one product in a Decomposition Reaction. | 
| Usually, heat or energy is produced in such reactions. | Usually, heat or energy is used in such reactions. | 
| General equation: A + B → C | General equation: A → B + C | 
| Example: CaO(s) + H 2 O(l) → Ca(OH) 2 (aq) | Example: CaCO 3 (s) → CaO(s) + CO 2 (g) | 
In the above two reactions, since the mechanism is opposite , they are called opposite reactions.
