This is because butterfly caterpillars are host specific. Plant-wise, the caterpillars of some butterfly species like asters, black-eyed Susan, clover, lupines, milkweed, sedum or violets. Aspen, birch, cherry, hackberry, oak or willow trees make caterpillars of other butterfly species equally happy.
each Br-F bond would be polar or BF4-, there is an extra electron making this a polar molecule. PCl5 has the Cl atoms that must be as far apart from each other as possible and therefore would create equal but opposite pulls.ach Br-F bond would be polar or BF4-, there is an extra electron making this a polar molecule. PCl5 has the Cl atoms that must be as far apart from each other as possible and therefore would create equal but opposite pulls.
I understand that SiCl4 is a tetrahedral therefore it has a permanent dipole which makes it non-polar but I dont understand why the bonds are polar and the actual SiCl4 is not.he next is dissymmetry-in other words it can't be symmetrical. Because SiCl4 has a sp3 hybridization and is tetrahedral in shape, it is therefore symetrical and cannot be a polar molecule. Source(s): old chem notes.