Atomic and Nuclear Physics
1 amu is equal to
  • 0.166 × 10⁻²⁷ kg
  • 1.77 × 10⁻²⁷ kg
  • 1.76 × 10⁻²⁷ kg
Explanation: 1 atomic mass unit (amu) is approximately 1.66 × 10⁻²⁷ kg, which is the average mass of a nucleon (proton or neutron) in an atom.
A good coolant possess
  • large specific heat capacity and low boiling point
  • low specific heat capacity and high boiling point
  • large specific heat capacity and high boiling point
  • low specific heat capacity and low boiling point
Explanation: A good coolant should have: Large specific heat capacity → To absorb and carry away more heat without a significant rise in temperature. High boiling point → To remain in liquid form and function effectively at high temperatures without evaporating. Example: Water is an excellent coolant because it has a high specific heat capacity and a high boiling point.
Energy of an electron when it is accelerated through a potential difference of 1 volt is
  • one becquerel
  • one electron volt
  • one curie
  • one roentgen
Explanation: The energy gained by an electron when it is accelerated through 1 volt is defined as 1 electron volt (eV). 1 eV = 1.6 × 10⁻¹⁹ joules. This is a fundamental unit of energy in atomic and particle physics.
The principle used in hydrogen bomb is
  • ionisation
  • chain reaction
  • nuclear fusion
  • nuclear fission
Explanation: The hydrogen bomb (or thermonuclear bomb) works on the principle of nuclear fusion, where lighter nuclei (like isotopes of hydrogen – deuterium and tritium) fuse to form heavier nuclei, releasing an enormous amount of energy. This process requires extremely high temperature and pressure, which is initially provided by a fission bomb (atomic bomb) as a trigger. Fusion releases much more energy than fission, making hydrogen bombs far more powerful.
In electromagnetic interactions the exchange particle is
  • positrons
  • neutrons
  • protons
  • photons
Explanation: Electromagnetic interactions occur between charged particles (like electrons and protons). These interactions are mediated by the exchange of photons (γ), which are the force carriers of the electromagnetic force in quantum electrodynamics (QED).
Mass defect is equal to
  • Assumed nuclear mass ÷ Real mass
  • Assumed nuclear mass × Real mass
  • Assumed nuclear mass + Real mass
  • Assumed nuclear mass - Real mass
Explanation: Mass defect is the difference between the total mass of individual nucleons and the actual nuclear mass. This lost mass is converted into binding energy, holding the nucleus together via Einstein’s equation E = mc sqr
Thermal neutrons have energy of about
  • 25 eV
  • 2.5 eV
    • Explanation: • Thermal neutrons are slow-moving neutrons that are in thermal equilibrium with their surroundings (usually at room temperature, around 300 K). • Their typical energy is approximately 0.025 eV, which corresponds to their average kinetic energy given by: E = 3/2kBT where kB is Boltzmann’s constant and T is the temperature in Kelvin. Thermal neutrons are crucial in nuclear reactors, as they efficiently induce fission in isotopes like Uranium-235.