Answer : The molecular formula of cyanide is,
and Lewis structure of cyanide is shown below.
Explanation :
Lewis-dot structure : It shows the bonding between the atoms of a molecule and it also shows the unpaired electrons present in the molecule.
In the Lewis-dot structure the valance electrons are shown by 'dot'.
The given molecule is,

As we know that carbon has '4' valence electrons, nitrogen has '5' valence electrons.
Therefore, the total number of valence electrons in
= 4 + 5 + 1 = 10
The skeleton structure of the compound, C molecule act as a central atom and is bonded to N with one sigma-bond and two pi-bonds with one negative charge.
Hence, the molecular formula of cyanide is,
and Lewis structure of cyanide is shown below.