In a neutral atom,which particles are equivalent in number?

State whether the following statements are true or false:
$(i)$ Isobars have different atomic numbers.
$(ii)$ $_{14}^{30}\text{Si}$,$_{16}^{32}\text{S}$ are isotones.
$(iii)$ Niels Bohr was the first to suggest that the atom is spherical.
$(iv)$ Rutherford's model is accepted as the nuclear model of the atom.

An element $_ZM^{19}$ has $10$ neutrons in its nucleus. To which block does it belong?

What do you understand by isoelectronic species? Name a species that will be isoelectronic with each of the following atoms or ions.
$(i)$ $F^{-}$
$(ii)$ $Ar$
$(iii)$ $Mg^{2+}$
$(iv)$ $Rb^{+}$

Which of the following has the smallest size?

The atoms $_6C^{13}$ and $_8O^{17}$ are related to each other as .......