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 $\dfrac{1}{2000}$ times that of a proton.

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

(a) False.

Reason — Thomson proposed that:

1. An atom consists of a positively charged sphere and the electrons are embedded in it.
2. The negative and positive charges are equal in magnitude. So, the atom as a whole is electrically neutral.

(b) False.

Reason — Neutron is not formed by an electron and a proton combining together. It is present in the nucleus of an atom alongside protons.

(c) True.

Reason — The mass of an electron is about $\dfrac{1}{2000}$ times that of a proton.

(d) False.

Reason — Tincture iodine is an antiseptic that usually contains 2-7% elemental I-127 dissolved in a mixture of ethanol and water. Normal iodine is used in its preparation, not its isotope. ​