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NDA 1 2025 GAT, question 72

Topic: Chemistry

Q72

Which one of the following statements is correct?

  1. (a) A neutron is formed by combination of an electron and a proton. Therefore, it is neutral
  2. (b) The mass of an electron is about 1/2000 times that of a protonCorrect answer
  3. (c) An isotope of cobalt is used in the treatment of goiter
  4. (d) J.J. Thomson proposed that the nucleus of an atom contains only neutrons

Solution.

Answer: (b) The mass of an electron is about 1/2000 times that of a proton

  1. An electron has about 1/1836 of a proton’s mass, reasonably approximated here as 1/2000.
  2. A neutron is not a bound proton–electron pair.
  3. Radioiodine, rather than cobalt, is the isotope associated with thyroid treatment; Thomson’s model did not contain a central neutron nucleus.