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

Hint:
Rutherford’s model showed different results than what was expected by Thomson’s model. In this experiment, most of the $\alpha$-particles went without being deflected.

Complete answer:
As Rutherford and his students bombarded a Gold foil with $\alpha$-particles, most of these particles went straight on and only few were deflected by a small angle. Some of them were also reflected totally.
- So, on the basis of the results obtained, they made a conclusion that atoms should have empty space and that space also should be big and only little volume is actually occupied by some mass. They termed that as the nucleus of the atom.
- They also concluded that there is free space around the nucleus and nucleus has positive charge as $\alpha$-particle got deflected by small angles. $\alpha$-particles also bear +2 positive charge as they are Helium cations.
- So the correct answer is (B) Mass and positive charge of an atom are concentrated in the nucleus.

Additional Information:
Rutherford made several conclusions based on $\alpha$-particle scattering experiment. They are as below.
- Most of the space in the atom is empty.
- As some of the $\alpha$-particles get deflected by small angles, so charged mass is concentrated in a very small volume.
- If Radius of an atom is ${10^{ - 10}}m$ then the radius of the nucleus is ${10^{ - 15}}m$.

Note:
- Same charges always repel each other and that is the reason why some particles got reflected because both particle and nucleus were having positive charges.
- Here option (A), (C) and (D) are also true statements but it does not have any connection with Rutherford’s experiment. So, be careful while choosing a proper answer.