Test: Rutherford's Model of an Atom - Class 9 MCQ

According to his experiment, Rutherford conclusion given below,
Rutherford's first conclusion is that the nucleus is smaller than the atom and second is that inside the atom electrons and nucleus are present. In the atom electrons revolve around the nucleus and rotate itself. The mass of the atom depends on the nucleus. The nucleus only has the maximum mass of the atom. The charge of the nucleus is positive and the charge of electrons is negative.

Only a few particles bounced back because the nucleus is so small / atom is mostly empty space that few collided with a nucleus . If they bounced back it was because of alpha particle and nucleus are positive : repulsion if they bounced back it was because nucleus is massive / dense so alpha particles rebound . "

1. Most of the space inside the atom is empty because most of the α-particles passed through the gold foil without getting deflected.
2. Very few particles were deflected from their path, indicating that the positive charge of the atom occupies very little space.
3. A very small fraction of α-particles were deflected by very large angles, indicating that all the positive charge and mass of the gold atom were concentrated in a very small volume within the atom.

From the data he also calculated that the radius of the nucleus is about 10⁵ times less than the radius of the atom.

Correct Option is D.
Rutherford Model of an atom:
On the basis of Rutherford's experiment,
(1) An atom consist of positively charged, dense and very small nucleus containing protons and neutrons. The entire mass of an atom is concentrated in the nucleus.

(2) The nucleus is surrounded by negatively charged electrons. The electrons are revolving around the nucleus in circular paths at very high speed. These circular paths of the electrons are called orbits.

(3) An atom is electrically neutral because the number of protons and electrons is equal.

Most of the alpha particles passed through the gold foil undeflected because most of the space inside the atom is empty.