Explain how one accounts for the fact that the bond angles in H$2$O are smaller $($~$104\backslash$deg $)$ than those in NH$3($~$107\backslash$deg $)?$ What type of interaction is the most repulsive $\_\_\_\_\_\_\_\_\_\_($BP$-$BP$,$ BP$-$LP$,$ or LP$-$LP$)?$