Answer:
Tetrahedral
Trigonal pyramidal
less than 109.5°
Explanation:
If a molecule has a hybridization of sp3 it must have four electron domains which corresponds to a tetrahedral geometry.
Now we were told that the molecule also has one lone pair. It means that one out of the four electron domains is composed of a lone pair. Thus the molecular geometry will be trigonal pyramidal (e.g NH3).
Recall that lone pairs usually decrease the bond angle to a value less than the expected value for that particular electron domain geometry.
The expected bond angle for a tetrahedral geometry is 109.5° but that of the trigonal planar geometry is less than this.
