Why is it difficult to separate compounds that have similar molecular structures?

See Explanation

Explanation:

Compounds with same molecular structures tends to have similar properties, Various separation techniques tends to use difference in properties such as solubility, melting and boiling point,  polarity, molecular interaction, and size to fail or become ineffective. This is very true in large biomolecules where the difference in composition is not sufficient to cause detectable change in properties, in fact, it is nearly impossible to prove that one molecule of biomolecular drugs, such as insulin, to be different from one another even though there are difference in molecular composition, and large scale separtion is not at all feasible.

on passing the small ampere of electric current through the tube made of ar and hg of cfl generates uv rays which excites the fluorescent and thus emits the high radiation by consumption of just 5- 12 w in comparison to incandescent light which requires more power such as around 40 - 55 w to lighten.

moreover the life span of fluorescent or cfl is around 8000 h whereas the life span of incandescent is around 1200 h

hence, the building installed with incandescent lights bears more electricity bill.