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.
BF3, XeF4 Symmetric ball shaped molecules such as tetrahedral and octahedral eg CF4 and SF6 The above apply in case of symmetrical substitution about the central atom eg CF4 is non polar but CH3F and CH2F2 and CHF3 are polar.xpect polar molecules in: V shaped (angular) molecules eg CF2 T shaped molecules eg ClF3 See-saw molecules eg SF4 Pyramidal molecules such as trigonal pyramidal or square pyramidal eg NF3, BrF5 Note: ClF3 and SF4 has to move in the polar molecules.