R4RIN – MCQs, Mock Tests | NCERT Class 12 MCQ Questions for Class 12 Physics Chapter 13 Nuclei

How many electrons are contained in 23892U nucleus?

1. 92
2. 146
3. 238
4. 0

✅ Correct Answer: 4

Chadwick was awarded the Nobel prize in Physics in 1935 for his discovery of:

1. electron
2. proton
3. neutron
4. None of the above

✅ Correct Answer: 3

The density of a nucleus is of the order of:

1. 1015 kg m-3
2. 1018 kg m-3
3. 1017 kg m-3
4. 1016 kg m-3

✅ Correct Answer: 3

When the mass of a sample of a radioactive substance decreases, the mean life of the sample:

1. increases
2. decreases
3. remain unchanged
4. first decreases then increases

✅ Correct Answer: 3

Alpha particle emitted from a radioactive material are:

1. Helium nuclei
2. Hydrogen nuclei
3. Lithium nuclei
4. None of the above

✅ Correct Answer: 1

The half life of a radioactive decay is n times its mean life, n is equal to:

1. 0.6930
2. 0.0693
3. 10.6930
4. 0.3070

✅ Correct Answer: 1

Rutherford is the unit of:

1. radioactivity
2. energy
3. photoelectric current
4. magnetic field

✅ Correct Answer: 1

According to Yukawa’s theory of nuclear forces, the origin of nuclear force between nucleons is due to the exchange of

1. mesons
2. photons
3. electrons
4. positrons

✅ Correct Answer: 2

An electron and a positron each having a mass equivalent to 0.53 MeV annihilate each other and produce a photon. The minimum energy of the photon is.

1. 0.53 MeV
2. 1.06 MeV
3. 2.12 MeV
4. zero

✅ Correct Answer: 2

The ground state energy of Hydrogen atom is -13.6 eV. What is the potential energy of electron in this state?

1. 0 eV
2. -13.6 eV
3. 2 eV
4. -27.2 eV

✅ Correct Answer: 4

The Bohr model of atom:

1. assumes that the angular momentum of electron is quantized
2. uses Einstein’s photoelectric equation
3. predicts continuous emission spectra for atoms
4. predicts the same emission spectra for all types of atoms

✅ Correct Answer: 1

Nuclear force is:

1. strong, short range and charge independent force
2. charge independent, attractive and long range force
3. strong, charge dependent and short range attractive force
4. long range, change dependent and attractive force

✅ Correct Answer: 1

If radio active nuclei emits β-particle, then mass-number:

1. increased by 1 unit
2. decreases by 1 unit
3. increases by 2 unit
4. decreases by 2 unit

✅ Correct Answer: 1

An alpha particle is emitted from 88Ra226, then the product nuclei has:

1. Z = 84, A = 224
2. Z = 86, A = 224
3. Z = 86, A = 222
4. Z = 82, A = 222

✅ Correct Answer: 3

X-ray was discovered by :

1. Becqueral
2. Marie curie
3. Roengton
4. Vanlaw

✅ Correct Answer: 3

Fusion takes place at high temperature because:

1. Atom are ionised at high temperature
2. Molecules break up at high temperature
3. Nuclei break up at high temp.
4. Kinetic energy is high enough to overcome repulsion between nuclei

✅ Correct Answer: 4

What percentage of radioactive substance is left after 5 half lives?

1. 3.125%
2. 6.25%
3. .33%
4. 31%

✅ Correct Answer: 2

The helium atom does not contain

1. two protons
2. two electrons
3. two neutrons
4. six nucleons

✅ Correct Answer: 4

The more readily fissionable isotope of uranium has an atomic mass of:

1. 234
2. 235
3. 236
4. 238

✅ Correct Answer: 2

Energy of electron in the 1st orbit of H-atom is:

1. -13.6 MeV
2. -13.6 eV
3. -13.6 J
4. 13.6 J

✅ Correct Answer: 2

The mass no. of a nucleus is M and its atomic no. is Z. The number of neutrons in the nucleus is :

1. M – Z
2. M
3. Z
4. M + Z

✅ Correct Answer: 1

The phenomena of radioactivity is:

1. Exothermic change with increase or decrease with temperature
2. increases on applied pressure
3. nuclear process does not depend on external factors
4. None of the above

✅ Correct Answer: 3