Radioactive decay is an example of:

Options

A. first order
B. second order
C. zero order
D. 0.5 order

Answer

### Step-by-Step Solution:

1. **Understanding Radioactive Decay**:
- Radioactive decay refers to the process by which unstable atomic nuclei lose energy by emitting radiation. This process results in the transformation of one element into another and is characterized by a decrease in the number of radioactive nuclei over time.

2. **Identifying the Order of Reaction**:
- In chemical kinetics, the order of a reaction is determined by how the rate of the reaction depends on the concentration of the reactants.
- For a reaction to be classified as first order, the rate of reaction must be directly proportional to the concentration of one reactant.

3. **Analyzing the Rate of Radioactive Decay**:
- The rate of radioactive decay can be expressed as:
\[ \text{Rate} = -\frac{d[N]}{dt} = k[N] \]
where \([N]\) is the concentration of the radioactive nuclei and \(k\) is the rate constant.
- This equation indicates that the rate of decay is proportional to the concentration of the radioactive nuclei present.

4. **Conclusion**:
- Since the rate of radioactive decay is directly proportional to the concentration of the radioactive nuclei, it is classified as a first-order reaction.

5. **Final Answer**:
- Therefore, radioactive decay is an example of a **first-order reaction**.