The volume of a nucleus is directly proportional to

• A

• A³

• $\sqrt{\mathrm{A}}$

• A^1/3

An electron is

• a hadron

• a baryon

• a nucleon

• a lepton

Two protons are kept at a separation of 40 $\stackrel{\circ }{\mathrm{A}}$. F_n is the nuclear force and F_e is the electrostatic force between them. Then

• F_n >> F_e

• F_n = F_e

• F_n << F_e

• F_n ≈ F_e

The ratio of the nuclear radii of elements with mass numbers 216 and 125 is

• 216 : 125

• $\sqrt{216} : \sqrt{125}$

• 6 : 5

• None of these

On bombarding U²³⁵ by slow neutron, 200 MeV energy is released. If the power output of atomic reactor is 1.6 MW, then the rate of fission will be

• 5 × 10²²/s

• 5 × 10¹⁶/s

• 8 × 10¹⁶/s

• 20 ×10¹⁶/s

The masses of two radioactive substances are same and their half-lives are 1 yr and 2 yr respectively. The ratio of their activities after 4 yr will be

• 1 : 4

• 1 : 2

• 1 : 3

• 1 : 6

₉₂U²³⁵ undergoes successive disintegrations with the end product of ₈₂Pb²⁰³. The number of α and β particles emitted are

• α = 6, β = 4

• α = 6, β = 0

• α = 8, β = 6

• α = 3, β = 3

The most stable particle in Baryon group is

• neutron

• omega-particle

• proton

• lambda-particle

In a radioactive disintegration, the ratio of initial number of atoms to the number of atoms present at an instant of time equal to its mean life is

• $\frac{1}{{\mathrm{e}}^2}$

• $\frac{1}{\mathrm{e}}$

• e

• e²

β- decay means emission of electron from

• innermost electron orbit

• a stable nucleus

• outermost electron orbit

• radioactive nucleus