These are short and simple. :) I've included my answers, tell me if I am wrong please.
CH3 is attached to a carbon on a pentane ring. Is the hybridization of the carbon sp3?
NH connects a benzene ring to two benzene rings. Is the hybridization of the nitrogen sp2?
OH is attached to a carbon on a pentane ring. Is the hybridization of the oxygen sp? I had issues with this one.
On a benzene ring, what is the hybridization of a carbon that has a double bond on one side and a single bond on the other? Is it sp2?
For the first question, CH3 attached to a carbon on a pentane ring, the hybridization of the carbon is indeed sp3. To determine the hybridization, you can count the number of regions of electron density surrounding the carbon, which includes both sigma and lone pair electrons. In this case, the carbon is bonded to three hydrogens and one other carbon, resulting in four regions of electron density and therefore sp3 hybridization.
For the second question, if NH connects a benzene ring to two benzene rings, the hybridization of the nitrogen is actually sp3. Nitrogen typically exhibits sp2 hybridization when it forms three sigma bonds and has no lone pairs. However, in this case, since the nitrogen is bonded to three benzene rings, it has four regions of electron density, which requires sp3 hybridization.
For the third question, OH attached to a carbon on a pentane ring, the hybridization of the oxygen is sp3. In this case, the oxygen is bonded to the carbon through a sigma bond and has two lone pairs of electrons. Since it has three regions of electron density, the hybridization is sp3.
And finally, for the last question, on a benzene ring, a carbon that has a double bond on one side and a single bond on the other is indeed sp2 hybridized. In a benzene ring, each carbon is bonded to two other carbons and one hydrogen, and the remaining two valence electrons form a pi bond with the neighboring carbon. This results in three regions of electron density and therefore sp2 hybridization.
Your answers were correct for the first and last questions, but the hybridization of the nitrogen in the second question is sp3 instead of sp2, and the hybridization of the oxygen in the third question is sp3 instead of sp.