Which statement is NOT correct about Rutherford’s model of the atom?

Analyze the question: We need the statement that is NOT correct about Rutherford's model of the atom.

Concept: Rutherford's model came from the alpha-particle scattering experiment (Geiger-Marsden gold foil experiment). It established that:

• Most of the atom is empty space.
• The atom has a very small, dense, positively charged nucleus at the centre.
• Nearly all the atom's mass is concentrated in the nucleus.
• Electrons orbit the nucleus (like planets around the Sun).
• The nucleus is very small, about 10⁻¹⁵ m to 10⁻¹⁴ m across, compared with the atom's roughly 10⁻¹⁰ m.

Checking each option:

• A. The nucleus has a diameter of the order of 10⁻¹⁵ m. This is accepted as correct (typical nuclear sizes are about 10⁻¹⁵ m).
• B. The mass of an atom is concentrated in the nucleus. This is correct, and it is a main conclusion of the model.
• C. The model is applicable only to atoms with one electron in the outer shell. This is wrong. Rutherford's model was a general model of the atom, based on gold atoms (79 electrons), so it was not limited to atoms with one outer electron. (If anything, the later Bohr model worked well only for hydrogen-like atoms.)
• D. The nucleus is positively charged. This is correct, and the alpha particles were deflected because of this.
• E. The nucleus is surrounded by an electron cloud. This is acceptable in the sense that electrons surround the nucleus, and it is the standard wording in this question bank. The "cloud" idea is a loose description of electrons around the nucleus.

Answer: The statement that is NOT correct is C.

Tip: For "NOT correct" questions, look for statements that are too restrictive, such as "only" or "applicable to atoms with one electron". Rutherford's model described the structure of atoms in general: a tiny, dense, positive nucleus holding nearly all the mass, with electrons around it.