Which of the following is not true in Rutherford’s nuclear model of atom

Options

A. Protons and neutrons are present inside nucleus
B. Volume of nucleus is very small as compared to volume of atom
C. The number of protons and neutrons are always equal
D. The number of electrons and protons are always equal

Explanation

To determine which statement is not true in Rutherford’s nuclear model of the atom, we will analyze each of the provided statements one by one.

### Step-by-Step Solution:

1. **Statement Analysis**:
- **Statement 1**: "Protons and neutrons are present in the nucleus."
- This statement is true. Rutherford's model states that the nucleus contains protons and neutrons.

2. **Statement 2**: "Electrons revolve around the nucleus."
- This statement is also true. According to Rutherford, electrons move in orbits around the nucleus.

3. **Statement 3**: "Electrons revolve in discrete orbits."
- This statement is not part of Rutherford's original model; it was introduced later by Niels Bohr. Therefore, this statement is misleading in the context of Rutherford's model.

4. **Statement 4**: "The volume of the nucleus is very small compared to the volume of the atom."
- This statement is true. Rutherford indicated that the nucleus is much smaller than the overall size of the atom.

5. **Statement 5**: "The number of protons and neutrons are always equal."
- This statement is false. Rutherford did not assert that protons and neutrons must be equal in number; they can vary. The atomic number (number of protons) does not have to equal the number of neutrons.

6. **Statement 6**: "The number of electrons and protons are always equal in a neutral atom."
- This statement is true. In a neutral atom, the number of electrons equals the number of protons.

### Conclusion:
The statement that is **not true** in Rutherford’s nuclear model of the atom is: **"The number of protons and neutrons are always equal."**