Nuclear Physics

Q: Heavy stable nuclei have more neutrons than protons. This is because of the fact that

(a) neutrons are heavier than protons

(b) electrostatic force between protons are repulsive

(c) neutrons decay into protons through beta decay

(d) nuclear forces between neutrons are weaker than that between protons

Ans: (b)

Q: The gravitational force between a H-atom and another particle of mass m will be given by Newton’s law F = G (M.m)/r² , where r is in km and

(a) M = m_proton + m_electron

(b) M = m_proton + m_electron -B/C² (B = 13.6 eV)

(c) M is not relate to the mass of the hydrogen atom.

(d) M = m_proton + m_electron -|V|/C² ; (|V| = magnitude of the potential energy of electron in the H-atom.

Ans: (b)

Q: Suppose we consider a large number of containers each containing initially 10000 atoms of a radioactive material with a half life of 1 yr. After 1 yr,

(a) all the containers will have 5000 atoms of the material

(b) all the containers will contain the same number of atoms of the material but that number will only be approximately 5000

(c) the container will in general have different numbers of the atoms of the material but their average will be close to 5000

(d) none of the containers can have more than 5000 atoms

Ans: (c)

Q: Two H atoms in the ground state collide inelastically. The maximum amount by which their combined kinetic energy is reduced is

(a) 10.20 eV

(b) 20.40 eV

(c) 13.6 eV

(d) 27.2 eV

Ans: (a)

Q: O2 molecule consists of two oxygen atoms, In the molecule, nuclear force between the nuclei of the two atoms

(a) is not important because nuclear forces are short-ranged

(b) is as important as electrostatic force for binding the two atoms

(c) cancels the repulsive electrostatic force between the nuclei

(d) is not important because oxygen nucleus have equal number of neutrons and protons

Ans: (a)