$A$ sodium cation $(Na^+)$ has a different number of electrons from which of the following species?

Assertion : The sum of protons and neutrons is always different in isobars.
Reason : Isobars are atoms of different elements having same mass number but different atomic number.

Which of the following species is $NOT$ isoelectronic with neon?

If the electronic configuration of a metal ion $M^{2+}$ is $2, 8, 14$ and its atomic mass is $56 \, a.m.u.$,then the number of neutrons in its nucleus is .....

The isobars are atoms with the same number of

The electronic configuration of a divalent metal ion $M^{2+}$ is $2, 8, 14$ and its atomic mass is $58 \, a.m.u.$ What is the number of neutrons in its nucleus?