paucity (n.) late 14c., from Old French paucitÃ© (14c.) and directly from Latin paucitatem (nominative paucitas) fewness, scarcity, a small number, from paucus few, little, from PIE *pau-ko-, suffixed form of root *pau-(1) few, little (source also of few (adj.)).
All three molecules have four pairs of electrons around their central atom. As a result, they all have a tetrahedral arrangment of electron pairs around the central atom. The bond angle in methane, CH4, is the tetrahedral angle, i.e. 109.5 (109 28'). Ammonia, NH3, contains a lone pair of electrons, which repels the bonding electrons to give a bond angle of 107. The atoms have a trigonal pyramidal arrangement.
C. SF6 90Â° (and 180Â°) This is octahedral with bond angles of 90 degrees D. AsF5 90Â°, 120Â° (and 180Â°) AsF5 is trigonal bipyramidal with bond angles of 120 and 90 degrees. E. BF3 120Â° BF3 is trigonal planar with bond angles of 120 degrees. The one that doesn't match is (B). AsH3 is polar.It is trigonal pyramidal and is asymmetrical. SbF5 is trigonal bipyramidal and is symmetrical and is therefore nonpolar.he one that doesn't match is (B). AsH3 is polar. It is trigonal pyramidal and is asymmetrical. SbF5 is trigonal bipyramidal and is symmetrical and is therefore nonpolar.