For the following statements, write T for True and F for False.

(a) J.J. Thomson proposed that the nucleus of an atom contains only nucleons.

(b) A neutron is formed by an electron and a proton combining together. Therefore, it is neutral.

(c) The mass of an electron is about 1/2000 times that of a proton.

(d) An radioactive isotope of iodine is used for making tincture iodine, which is used as a medicine.

 

Answer

 

(a) J.J. Thomson proposed that the nucleus of an atom contains only nucleons.

     False

 

Explanation - JJ Thomson’s model only talked about the positive and negative charges, ie, protons and electrons but didn’t mention the presence of nucleus or nucleons (subatomic particles inside nucleus)

 

(b) A neutron is formed by an electron and a proton combining together. Therefore, it is neutral.

False

 

Explanation - Proton, electron and neutron are three different and independent subatomic particles.

 

 

(c) The mass of an electron is about 1/2000 times that of a proton.

     True

 

Explanation - Protons are around 2000 times heavier than electrons, which means the mass of an    electron is about 1/2000 times that of a proton, hence mass of electron is negligible.

 

 

(d) A radioactive isotope of iodine is used for making tincture iodine, which is used as a medicine.

False

 

Explanation - Since tincture of iodine is the combination of 5% - 7% of iodine, water and alcohol. And the iodine used here is the ordinary iodine , that is, no radioactive isotope of iodine is present.

 

  1. Class 9
  2. Chapter 4 Class 9 - Structure of Atom (Term 2)

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CA Maninder Singh
CA Maninder Singh is a Chartered Accountant for the past 11 years and a teacher from the past 11 years. He teaches Science, Accounts and English at Teachoo