The H–N–H bond angle in NH3 (about 107∘) is smaller than the H–C–H bond angle in CH4 (109.5∘). Which of the following best explains this difference?
a) Nitrogen is sp2 hybridized, so its trigonal-planar arrangement compresses the H–N–H angle relative to the tetrahedral angle in CH4.
b) Nitrogen’s smaller atomic radius forces the hydrogens closer together, leading to a smaller bond angle.
c) A lone pair on nitrogen exerts greater repulsion on bonding pairs than a bonding-pair–bonding-pair interaction in methane.
d) Hydrogen bonding among ammonia molecules distorts the intramolecular bond angles, reducing the H–N–H angle.