Lewis structures, octet rule, formal charge

18 questions on Lewis structures, octet rule, formal charge from the Chemical Bonding chapter: 5 NEET level, 8 JEE Main, 5 JEE Advanced. Each one opens with its answer and solution.

• What is the formal charge on the nitrogen atom in NH4+? NEET level
• In which of the following molecules does the central atom have an incomplete octet (only six electrons) in its Lewis structure? NEET level
• How many lone pairs are present on the central atom of H2O? NEET level
• Which of the following species contains an odd number of valence electrons? NEET level
• The numbers of sigma and pi bonds in C2H4 are, respectively, NEET level
• In the Lewis structure of ozone drawn as O=O+-O-, the formal charges on the terminal double-bonded O, the central O and the terminal single-bonded O are, respec... JEE Main level
• In its Lewis structure, which of the following species has more than eight electrons around the central atom? JEE Main level
• The total number of coordinate (dative) covalent bonds in one formula unit of NH4BF4 (i.e. NH4+ together with BF4-) is JEE Main level
• In which of the following species is there a triple bond between the two atoms in the best Lewis structure? JEE Main level
• In the Lewis structure of CO with a triple bond and one lone pair on each atom, the formal charges on C and O are, respectively, JEE Main level
• The total number of lone pairs on all atoms in the Lewis structure of acetic acid, CH3COOH, is JEE Main level
• In the Lewis structure of nitrous oxide written as N#N+-O-, the formal charge on the central nitrogen atom is JEE Main level
• In the symmetric Lewis structure of the azide ion N3- with two N=N double bonds, the formal charges on the three nitrogen atoms (left, centre, right) are, respe... JEE Main level
• Aspirin (2-acetoxybenzoic acid, C9H8O4) has a benzene ring carrying a -COOH group and, on the adjacent carbon, an -O-CO-CH3 group. Counting each bond's sigma co... JEE Advanced level
• Hydrazoic acid is written as H-N=N+=N-. The number of sigma bonds, the number of pi bonds and the total number of lone pairs in this structure are, respectively... JEE Advanced level
• The nitrate ion is drawn with one N=O and two N-O^- bonds. Which of the following statements about this single structure are correct? JEE Advanced level
• Phosphorous acid, H3PO3, is drawn with one P=O, two P-OH and one P-H bond (P has no lone pair). The total number of lone pairs on all atoms is JEE Advanced level
• Nitryl chloride, NO2Cl, has N as the central atom bonded to Cl, to one O by a double bond and to the other O by a single bond. Considering a Lewis structure in ... JEE Advanced level