Which of the following are identical in terms of their atomic number $(Z)$?
$(i)$ $Na$ and $Na^+$
$(ii)$ $F$ and $F^-$

The atomic configurations of atoms $A$,$B$,and $C$ are given as: $A = [Z(90) + n(146)]$,$B = [Z(92) + n(146)]$,$C = [Z(90) + n(148)]$. Which of the following statements are incorrect?
$(a) A$ and $C$ are isotones.
$(b) A$ and $C$ are isotopes.
$(c) A$ and $B$ are isobars.
$(d) B$ and $C$ are isobars.
$(e) B$ and $C$ are isotopes.

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

Assertion : Atoms are not electrically neutral.
Reason : Number of protons and electrons are different.

Which of the following is not a hydrogen-like species?

Calculate the number of electrons,protons,and neutrons in $Cl_{2}$,$Cl$,and $Cl^{-}$. (Given for $Cl$: $Z = 17$ and $A = 35$)