The ion having the highest bond order is

Concept:-

Bond order:

• Bond order is the number of bonding pairs of electrons between two atoms.
• In a covalent bond; a single bond has a bond order of one, a double bond has a bond order of two, and a triple bond has a bond order of 3
• Nonbonding electrons and antibonding electrons are not considered for the determination of the bond order.

Bond order

= \({{\left( {{\rm{Number\; of\; electrons\; in\; BMO - Number\;of\; electrons\; in\; ABMO}}} \right)} \over {\rm{2}}}\).

Explanation:

• The MO diagram of the NO molecule is given below:

​

• NO (Nitric oxide) has 11 valence shell electrons (excluding 1s orbital electrons).
• The electronic configuration of NO is

\(1{\sigma ^2}2{\sigma ^2}3{\sigma ^2}1{\pi ^4}2{\pi ^1}\)

Now, for NO+ the total number of electrons (excluding 1s orbital electrons) is
= (11-1)

= 10

The electronic configuration of NO⁺ will be as follows:

\(1{\sigma ^2}2{\sigma ^2}3{\sigma ^2}1{\pi ^4}\)

So, B.O. = \({{\left( {{\rm{Number\; of\; electrons\; in\; BMO - Number\;of\; electrons\; in\; ABMO}}} \right)} \over {\rm{2}}}\)

= \({{\left( {{\rm{6-0}}} \right)} \over {\rm{2}}}\) (As, \(3{\sigma }\:and\:1{\pi }\:both \:are\:bonding\:M.O\))

= 3 

Similarly, B.O. of O₂⁺ , N₂⁺ and C₂⁺ are 2.5, 2.5 and 1.5 respectively

Conclusion:

•  Hence NO⁺ has the highest B.O. among others i.e.3.