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
Alpha particle emitted from a radioactive material are:
1. Helium nuclei
2.Hydrogen nuclei
3.Lithium nuclei
4.None of the above
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
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
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
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
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
How many electrons are contained in 23892U nucleus?
1.92
2.146
3.238
4.0
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
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
Rutherford is the unit of:
1.radioactivity
2.energy
3.photoelectric current
4.magnetic field
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
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
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
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
The helium atom does not contain
1. two protons
2. two electrons
3.two neutrons
4.six nucleons
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
The more readily fissionable isotope of uranium has an atomic mass of:
1.234
2.235
3.236
4. 238
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
What percentage of radioactive substance is left after 5 half lives?
1. 3.125%
2.6.25%
3..33%
4.31%
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
X-ray was discovered by :
1.Becqueral
2. Marie curie
3.Roengton
4.Vanlaw