Decomposition reactions are reverse of

Options

A. chemical reaction
B. chemical change
C. combination reaction
D. displacement reaction.

Answer

### Step-by-Step Text Solution:

1. **Understanding Decomposition Reactions**:
- A decomposition reaction is a type of chemical reaction where one reactant breaks down into two or more simpler products.
- For example, potassium chlorate (KClO3) decomposes upon heating to form potassium chloride (KCl) and oxygen gas (O2).

2. **Identifying the Reverse Reaction**:
- To find the reverse of a decomposition reaction, we need to look for a reaction that combines simpler substances to form a more complex substance.
- This is known as a combination reaction, where two or more reactants combine to produce one product.

3. **Example of a Combination Reaction**:
- An example of a combination reaction is when hydrogen gas (H2) and chlorine gas (Cl2) react to form hydrogen chloride (HCl).
- Here, two gases combine to form a single product, which is the opposite of what happens in a decomposition reaction.

4. **Conclusion**:
- Therefore, we can conclude that decomposition reactions are the reverse of combination reactions.
- In summary, the correct answer to the question is that decomposition reactions are the reverse of combination reactions.