A free neutron decays spontaneously into

Options

A. a proton, an electron and an anti neutrino
B. a proton, an electron and a neutrino
C. a proton and electron
D. a proton, an electron, a neutrino and an anti neutrino

Answer

To solve the question regarding the spontaneous decay of a free neutron, we can follow these steps:

### Step 1: Understand the Composition of a Neutron
A neutron is a neutral baryon found in the nucleus of an atom. It is made up of three quarks: one up quark and two down quarks (udd).

### Step 2: Identify the Decay Process
In a free state, a neutron undergoes beta decay. This process involves the transformation of one of its down quarks into an up quark, which results in the formation of a proton.

### Step 3: Write the Decay Equation
The decay of a neutron can be represented by the following equation:
\[ n \rightarrow p + e^- + \overline{\nu} \]
Where:
- \( n \) is the neutron,
- \( p \) is the proton,
- \( e^- \) is the emitted electron (beta particle),
- \( \overline{\nu} \) is the antineutrino.

### Step 4: Analyze the Options
Now, let's analyze the provided options:
1. Proton, electron, or anti-neutron
2. Proton, electron, or neutrino
3. Proton, electron, and a proton
4. Proton, electron, neutrino, and an anti-neutron

From our decay equation, we see that the neutron decays into a proton, an electron, and an antineutrino. Therefore, the correct option must include these particles.

### Step 5: Select the Correct Answer
The correct answer is:
**Proton, electron, and an antineutrino**.

### Final Answer
A free neutron decays spontaneously into a proton, an electron, and an antineutrino.

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