On the basis of Thomson's model of an atom,explain how the atom is neutral as a whole.

Name the three sub-atomic particles of an atom.

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

Summarize the rules for writing the distribution of electrons in various shells for the first eighteen elements.

If $K$ and $L$ shells of an atom are full,then what would be the total number of electrons in the atom?

Explain with examples $(i)$ Atomic number,$(ii)$ Mass number. Give any two uses of isotopes.