Question

Which statement is correct about CN and $C{N^-}$ ?
A. Both are paramagnetic with bond order 5/2 and 3 respectively
B. Both are diamagnetic with bond order 5/2 and 3 respectively
C. CN is paramagnetic with bond order 3, $C{N^-}$ is diamagnetic with bond order 5/2
D. CN is paramagnetic with bond order 2.5, $C{N^-}$ is diamagnetic with bond order 3

Answer 1

Hint: Maybe one could be paramagnetic and other one is diamagnetic and the total electrons of CN are $13$ with $1$ unpaired electron.

Complete answer:
CN is paramagnetic in nature and the bond order is $2.5$ and as it has $13$ electrons along with $1$\[98\% \] unpaired electron therefore it is paramagnetic by nature with bond order of $1/2(72) = 2.5$.
$C{N^-}$ is diamagnetic in nature and the bond order is $3$ and as it has $14$ electrons with all paired and no unpaired electrons, hence it is diamagnetic by nature with bond order of $1/2(82) = 3$.

Hence, Option D is correct.

Additional information:
A cyanide is a chemical element which contains the group C≡N. This group, is known as the cyano group, contains a carbon atom triple-bonded to a nitrogen atom. In an inorganic cyanide, the cyanide group presence is there as the anion $C{N^-}$.
Molar mass of CN is \[26.018\]g/mol.
A carbon–nitrogen bond is actually a covalent bond b/w carbon and nitrogen and it is 1 of the most abundant bonds in organic chemistry and biochemistry. For the same reason a lot of compounds having CN bonds are soluble in water.
Intramolecular covalent bonds are the ones which are really hard to break and also they are very stable, being almost \[98\% \] stronger than intermolecular bonds.

Note:
Observe the hint carefully, it will become easy to decode the answer. As one is diamagnetic and the other one is paramagnetic in nature, so bond order can also be calculated with the help of the number of electrons.