The lone pairs on pyrimidine are not delocalized because of which factor?

a. The lone pairs are in sp3 orbitals.

b. The lone pairs are in sp orbitals.

c. The lone pairs are in orbitals at 90 degrees to the pi system.

d. None of the above.

The question is incorrect. It should read:

The lone pairs on pyrimidine are delocalized because of which factor?

a. The lone pairs are in sp3 orbitals.

b. The lone pairs are in sp orbitals.

c. The lone pairs are in orbitals at 90 degrees to the pi system.

d. None of the above.

Answer:

d. None of the above.

Explanation:

The nitrogen in pyrimidine is not sp³ hybridized. That means that this pair of electrons is not localized to this nitrogen and is free to move, which is actually what gives rise to pyramidine's resonant structures.