Indigo is an organic compound that is a derivative of indole. Most of the indigo dye produced today is consumed to dye cotton yarn - to make denim and blue jeans. The chemical structure of indigo is given below. Determine the number of unhybridized orbitals on N and C atoms in indigo. [Hint: Due to resonance stabilization/aromaticity N is sp² hybridized.]

• A. N = 0 unhybridized orbitals; C = 16 unhybridized orbitals
• B. N = 2 unhybridized orbitals; C = 16 unhybridized orbitals
• C. N = 1 unhybridized orbitals; C = 14 unhybridized orbitals
• D. N = 2 unhybridized orbitals; C = 12 unhybridized orbitals

Answer: (B)