Modern Physics
Isotopes have the same
  • Atomic number
  • Mass number
  • Avogadro’s number
  • None of these
Explanation: Isotopes are atoms of the same element that have the same atomic number (same number of protons) but different mass numbers (different number of neutrons).
The main source of solar energy is
  • Combustion
  • Nuclear fission
  • Nuclear fusion
  • None of these
Explanation: The Sun produces energy through nuclear fusion, where hydrogen nuclei fuse to form helium, releasing a tremendous amount of energy in the form of light and heat.
Nuclear forces are
  • Long range
  • Spin dependent
  • Charge dependent
  • None of these
Explanation: Nuclear forces are short-range but spin-dependent, meaning their strength depends on the spin alignment of nucleons (protons and neutrons). They are also charge-independent, acting similarly between proton-proton, neutron-neutron, and proton-neutron pairs.
When the speed of electrons increases, then the value of the specific charge on an electron
  • Increases
  • Decreases
  • Remains unchanged
  • None of these
Explanation: Due to relativistic effects, as the speed of an electron increases, its relativistic mass increases. Since specific charge is given by 𝑒/𝑚 , an increase in mass leads to a decrease in the specific charge.
Nuclear forces are mediated by
  • Proton
  • Neutron
  • Meson
  • Electron
Explanation: Nuclear forces are mediated by mesons, which act as exchange particles between nucleons (protons and neutrons) to hold the atomic nucleus together.
An atom bomb is based upon the principle of
  • Controlled nuclear fission
  • Nuclear fusion
  • Nuclear fission
  • None of the above
Explanation: An atom bomb is based on the principle of nuclear fission, where a heavy nucleus (like uranium-235 or plutonium-239) splits into smaller nuclei, releasing a huge amount of energy.
The first explosion of an atomic device in India was carried out in the state of
  • Rajasthan
  • Explanation: The first explosion of an atomic device in India was carried out in the state of (A) Rajasthan at Pokhran on 18 May 1974. It was called "Smiling Buddha."