The electron, neutron, and proton, listed in descending order of mass are

Options

A. Electron, neutron, proton
B. Electron, proton, neutron
C. Proton, neutron, electron
D. Neutron, proton, electron

Answer

To list the electron, neutron, and proton in descending order of mass, we can follow these steps:

### Step 1: Identify the Mass of Each Particle
- **Electron (e)**: The mass of an electron is approximately \(9.11 \times 10^{-31}\) kg or about \(0.00054858\) atomic mass units (u).
- **Proton (p)**: The mass of a proton is approximately \(1.67 \times 10^{-27}\) kg or about \(1.007276\) u.
- **Neutron (n)**: The mass of a neutron is approximately \(1.68 \times 10^{-27}\) kg or about \(1.008665\) u.

### Step 2: Compare the Masses
- From the values identified, we can see that:
- Neutron: \(1.008665\) u
- Proton: \(1.007276\) u
- Electron: \(0.00054858\) u

### Step 3: Arrange in Descending Order
- Since we are arranging in descending order of mass, we start with the heaviest:
1. Neutron (n)
2. Proton (p)
3. Electron (e)

### Final Answer
The order of the particles in descending order of mass is:
**Neutron > Proton > Electron**