To differentiate between carbon-$12$,carbon-$13$ and carbon-$14$,the instrument that you would use is

If the atomic weight of an element is $23$ times that of the lightest element and it has $11$ protons,then it contains

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.

The total number of neutrons in dipositive zinc ions with mass number $70$ is

Identify the isoelectronic species from the following groups.

Which character is different for the two isotopes of an element?