The Lewis Structure of Nitromethane is attached below.
It can be found from structure that it consists of a single carbon atom bonded to three hydrogen atoms and a nitrogen atom of Nitro functional group via single covalent (sigma) bonds.
The functional group (-NO₂) is highlighted in blue.
Also, the formal charges on all atoms is zero except for Nitrogen atom and and oxygen atom of Nitro group which was calculated +1 and -1 respectively using following formula.
Formal Charge = [# of valence e⁻] - [e⁻ in lone pairs + 1/2 # of bonding e⁻]
