Question

Rutherford's $\alpha$-particle scattering experiment led to the conclusion that:

• A. mass and energy are related
• B. mass and positive charge of an atom are concentrated in the nucleus
• C. neutrons are present in the nucleus
• D. atoms are electrically neutral

Answer 1

The correct option is B mass and positive charge of an atom are concentrated in the nucleus

Postulates of the Rutherford atomic model based on observations and conclusions:

1. An atom is composed of positively charged particles. Majority of the mass of an atom was concentrated in a very small region. This region of the atom was called as the nucleus of an atom. It was found out later that the very small and dense nucleus of an atom is composed of neutrons and protons.
2. Atoms nucleus is surrounded by negatively charged particles called electrons.
3. The electrons revolve around the nucleus in a fixed circular path at very high speed. These fixed circular paths were termed as “orbits.”
4. An atom has no net charge or they are electrically neutral because electrons are negatively charged and the densely concentrated nucleus is positively charged. A strong electrostatic force of attractions holds together the nucleus and electrons.
5. The size of the nucleus of an atom is very small in comparison to the total size of an atom.

Thus, Rutherford's α-particle scattering experiment led to the conclusion that the mass and positive charge of an atom is concentrated in the nucleus

Hence, the correct option is $\text{B}$