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.
polar, nonpolar, you've spotted those adequately. The thing to remember now is that molecules don't know they're polar or nonpolar, those are just names we come up with to describe our observations. In the case of ethanol, it has a polar bit and a non polar bit- the 'anol' vs the 'eth'. In this molecule, the carbon end is nonpolar enough to drag the polar end into the tolune, and vice versa, the polar end is polar enough as to drag the nonpolar end into water, which is why alcohol mixes with water.