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 $\frac {1}{ 2000}$ times that of proton.

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

• A

  $(a)-(T)\;;\;(b)-(F)\;;\;(c)-(T)\;;\;(d)-(F)$

• B

  $(a)-(F)\;;\;(b)-(T)\;;\;(c)-(T)\;;\;(d)-(F)$

• C

  $(a)-(F)\;;\;(b)-(F)\;;\;(c)-(T)\;;\;(d)-(F)$

• D

  $(a)-(T)\;;\;(b)-(F)\;;\;(c)-(F)\;;\;(d)-(T)$