Case Study Questions for Class 12 Physics Chapter 13 Nuclei

Case Study Question 1:

Read the passage given below and answer the following questions:

Neutrons and protons are identical particle in the sense that their masses are nearly the same and the force, called nuclear force, does into distinguish them. Nuclear force is the strongest force. Stability of nucleus is determined by the neutron proton ratio or mass defect or packing fraction. Shape of nucleus is calculated by quadrupole moment and spin of nucleus depends on even and odd mass number. Volume of nucleus depends on the mass number. Whole mass of the atom (nearly 99%) is centred at the nucleus.

(i) The correct statements about the nuclear force is/are
(a) charge independent
(b) short range force
(c) non-conservative force
(d) all of these.

(ii) The range of nuclear force is the order of
(a) 2 x 10^-10 m
(b) 1.5 x 10^-20 m
(c) 1.2 x 10^-4 m
(d) 1.4 x 10^-15 m

(iii) A force between two protons is same as the force between proton and neutron. The nature of the force is
(a) electrical force
(b) weak nuclear force
(c) gravitational force
(d) strong nuclear force

(iv) two protons are kept at a separation of 40 A⁰. F_n is the nuclear force and F_e is the electrostatic force between them. Then
(a) F_n <<F_e
(b) F_n= F_e
(c) F_n >> F_e
(d) F_n ≈ F_e

(v) All the nucleons in an atom are held by
(a) nuclear forces
(b) vander waal’s forces
(c) tensor forces
(d) coulomb forces

Answer

(i) d
Explanation: All options are basic properties of nuclear forces. So, all options are correct.
(ii) d
Explanation: The nuclear force is of short range and the range of nuclear force is the order of 1.4×10^-14m.
Now, volume α R³ α A
(iii) d
(iv) a
(v) a