Question

CO is isoelectronic with

• A. ${\mathrm{NO}}^{+}$
• B. ${\mathrm{N}}_2$
• C. ${\mathrm{SnCl}}_2$
• D. ${\mathrm{NO}}_2$

Answer 1

Answer: (A), (B)

${\mathrm{N}}_2$

Explanation for correct answer:

Option (A): $N{O}^{+}$

• Isoelectronic species have the same number of electrons but the individual atoms may be different.
• Isoelectronic species may be a molecule or an ion.
• In the case of $CO$, it has 14 electrons.
• $N{O}^{+}$has 14 electrons.
• Thus, $N{O}^{+}$ and $CO$ are isoelectronic species.

Option (B) : $N_2$

• $N_2$ has 14 electrons.
• $N_2$and $CO$ both have the same number of electrons i.e., 14 electrons.
• Thus, $N_2$ and $CO$ are isoelectronic species.

Explanation for incorrect answer:

Option (C) : $SnC{l}_2$

• $SnC{l}_2$ has 82 electrons.
• For a species to be isoelectronic the species must have to have the same number of electrons.
• $SnC{l}_2$ has 82 electrons, whereas $CO$ has 14 electrons.
• Thus, $SnC{l}_2$and $CO$ are not isoelectronic.

Option (D) : $N{O}_2$

• $N{O}_2$ has 23 electrons.
• For a species to be isoelectronic the species must have to have the same number of electrons.
• $N{O}_2$ has 23 electrons, whereas $CO$ has 14 electrons.
• Thus, $N{O}_2$ and $CO$ are not isoelectronic.

Therefore, the correct options are (A) and (B).