Which of the following is not a fundamental particle ?

Options

A. Proton
B. Neutron
C. Alpha particle
D. Electron

Answer

To determine which of the following options is not a fundamental particle, we need to understand the definition of fundamental particles in the context of atomic structure. Fundamental particles are the smallest constituents of matter that cannot be broken down into smaller components.

Let's analyze each option provided:

1. **Proton**:
- Protons are positively charged particles found in the nucleus of an atom. They are considered fundamental particles as they are one of the basic building blocks of atomic structure.

2. **Neutron**:
- Neutrons are neutral particles also located in the nucleus of an atom. Like protons, they are fundamental particles that contribute to the atomic mass but do not carry a charge.

3. **Electron**:
- Electrons are negatively charged particles that orbit the nucleus of an atom. They are fundamental particles as well, as they are not made up of smaller components.

4. **Alpha particle**:
- An alpha particle is a type of particle that consists of 2 protons and 2 neutrons (essentially a helium nucleus). Since it is made up of protons and neutrons, it is not considered a fundamental particle.

Based on this analysis, the answer to the question "Which of the following is not a fundamental particle?" is **Alpha particle**.

### Step-by-Step Solution:
1. **Identify the definition of fundamental particles**: Fundamental particles are the smallest constituents of matter.
2. **Analyze each option**:
- Protons: Fundamental particle (part of the nucleus).
- Neutrons: Fundamental particle (part of the nucleus).
- Electrons: Fundamental particle (orbiting the nucleus).
- Alpha particle: Not a fundamental particle (composed of protons and neutrons).
3. **Conclude the answer**: The alpha particle is not a fundamental particle.