The charge/mass (e/m) ratio is maximum for

Options

A. proton
B. neutron
C. electron
D. positron

Answer

To determine for which particle the charge/mass (e/m) ratio is maximum, we will analyze the charge and mass of protons, neutrons, electrons, and positrons.

### Step 1: Understand the charge and mass of each particle
- **Proton (H⁺)**: Charge = +1, Mass = 1 (in atomic mass units)
- **Neutron (n)**: Charge = 0, Mass = 1
- **Electron (e⁻)**: Charge = -1, Mass ≈ 0 (very small, often considered negligible)
- **Positron (e⁺)**: Charge = +1, Mass ≈ 0 (similar to electron)

### Step 2: Calculate the e/m ratio for each particle
- **Proton**:
\[ \frac{e}{m} = \frac{+1}{1} = 1 \]

- **Neutron**:
\[ \frac{e}{m} = \frac{0}{1} = 0 \]

- **Electron**:
\[ \frac{e}{m} = \frac{-1}{0} \rightarrow \text{undefined (approaches infinity)} \]

- **Positron**:
\[ \frac{e}{m} = \frac{+1}{0} \rightarrow \text{undefined (approaches infinity)} \]

### Step 3: Compare the ratios
- The e/m ratio for the proton is 1.
- The e/m ratio for the neutron is 0.
- The e/m ratio for the electron and positron approaches infinity, but since we cannot have a defined mass of 0, we typically do not consider these cases for practical calculations.

### Step 4: Conclusion
The charge/mass (e/m) ratio is maximum for the **proton**, as it has a defined ratio of 1 compared to the other particles.

### Final Answer
The charge/mass (e/m) ratio is maximum for the **proton**.

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