Isotopes of the same element have the same number of

The ratio of the number of neutrons in $_6C^{12}$ and $_{14}Si^{28}$ is ....

Which from the following statements is $NOT$ true about isotopes?

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

What is the representation of an element having a mass number of $40$ and $21$ neutrons in it?

The symbol of an isotope is $_{32}X^{65}$,this reveals that