describe the hybridization (sp3, sp2, sp) of the following bonds.

BH3 (all single bonds)
Is it sp2?

H-C triple bond C-H
Is it sp?

A double bond with two methyls connected at each end
Is it sp2?

Please Help ASAP

yes, yes, yes although the last one must have something else attached to the two middle C atoms. As they stand they are trivalent and C doesn't like that. I assume you mean CH3C=CCH3 or more exactly, CH3CH=CHCH3.

To determine the hybridization of a bond, you need to consider both the number of sigma bonds and the number of lone pairs of electrons around the central atom. The different hybridization types correspond to different geometries and bond angles.

In BH3, boron is the central atom with three single bonds to hydrogen. Since there are no lone pairs of electrons around boron, we can determine the hybridization based solely on the number of sigma bonds. In this case, BH3 has three sigma bonds, indicating sp2 hybridization.

For the H-C triple bond C-H, there are two carbon atoms involved, each with two sigma bonds (one to a hydrogen atom and one to the other carbon atom). Additionally, each carbon atom has only one lone pair of electrons. This combination of two sigma bonds and one lone pair suggests sp hybridization.

In the case of a double bond with two methyls connected at each end, the central atom is again carbon. Here, each carbon atom is connected to two other atoms (one hydrogen from the methyl group and one carbon from the other methyl group) with one sigma bond each. Additionally, each carbon atom forms a double bond with the other carbon atom, which involves one pi bond. Since each carbon atom has two sigma bonds and no lone pairs, the hybridization is sp2.