Out of the following , which one is not emitted by a natural radioactive substance ?

Options

A. Electrons
B. Electronmagnetic radiations
C. Helium nuclei with charge equal to that of two protons
D. Neutrons

Answer

To determine which of the following is not emitted by a natural radioactive substance, we need to analyze the common emissions from such substances. Natural radioactive decay typically involves the emission of alpha particles, beta particles, and gamma rays.

### Step-by-Step Solution:

1. **Identify Common Emissions from Radioactive Substances**:
- Natural radioactive substances emit three primary types of radiation:
- **Alpha particles**: These are helium nuclei, consisting of 2 protons and 2 neutrons.
- **Beta particles**: These are high-energy, high-speed electrons (or positrons) emitted from a nucleus.
- **Gamma rays**: These are electromagnetic radiation emitted from the nucleus during radioactive decay.

2. **Examine the Options**:
- **Helium Nucleus (Alpha particle)**: This is emitted during alpha decay.
- **Electrons (Beta particles)**: These are emitted during beta decay.
- **Gamma Radiation**: This is emitted as electromagnetic radiation during decay processes.
- **Neutrons**: Neutrons are not typically emitted during natural radioactive decay processes.

3. **Conclusion**:
- Among the options provided, neutrons are not emitted by natural radioactive substances. Therefore, the correct answer is that neutrons are the emissions that do not occur in natural radioactivity.

### Final Answer:
Neutrons are not emitted by a natural radioactive substance.

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