The number of protons,neutrons,and electrons in the element $_{89}X^{231}$ are respectively:

Which one of the following sets of ions represents a collection of isoelectronic species? (Given: Atomic Number: $F: 9, Cl: 17, Na: 11, Mg: 12, Al: 13, K: 19, Ca: 20, Sc: 21$)

Compared with an atom of atomic weight $12$ and atomic number $6$,the atom of atomic weight $13$ and atomic number $6$:

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

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

The electronic configuration of a dipositive metal $M^{2+}$ is $2, 8, 14$ and its atomic weight is $56 \ a.m.u.$ The number of neutrons in its nuclei would be