Question

The ion that is isoelectronic with CO is:
a.) ${{N}_{2}}^{+}$
b.) $C{{N}^{^{\_}}}$
c.) ${{O}_{2}}^{+}$
d.) ${{O}_{2}}^{-}$

Answer 1

Hint: Ions which are isoelectronic have the same number of electrons as Iso means same and electronic means electron. Number of electrons is the same as the atomic number. A positive ion is formed when an electron is donated.

Complete step by step answer:
Ions that are isoelectronic have the same number of electrons.
-Number of electrons present are indicated by atomic number.
-cations are formed when electrons are lost and anions are formed when electrons are gained.
-In CO, carbon has six electrons and oxygen has eight electrons so total number of electrons are 6 + 8 = 14

-In ${{N}_{2}}^{+}$, nitrogen has seven electrons, +1 as charge indicates one electron is donated, so total number of electrons are 7 + 7 - 13

-In $C{{N}^{-}}$, Carbon has six electrons and nitrogen has seven electrons and -1 as charge indicates one electron is gained, so total number of electrons are 6 + 7 + 1 = 1

-In ${{O}_{2}}^{+}$, oxygen has eight electrons and +1 indicates one electron is donated so total number of electrons are 8 + 8 - 1 = 15

-In ${{O}_{2}}^{-}$ , oxygen has eight electrons and -1 indicates one electron is accepted so total number of electrons are 8 + 8 + 1 = 17
As, total number of electrons in CO and $C{{N}^{-}}$ are 14, so the ion that is isoelectronic with CO is (B) $C{{N}^{-}}$
So, the correct answer is “Option B”.

Note: Ions that are isoelectronic have the same number of electrons. The number of electrons present are indicated by atomic number. cations are formed when electrons are lost and anions are formed when electrons are gained. nitrogen has seven electrons, oxygen has eight electrons, Carbon has six electrons.