18) What is the relationship between Ha and Hb in the following compound? A) Mesotopic B) Enantiotopic C) Diastereotopic D) Homotopic 19) What is the relationship between Ha and Hb in the following compound? Ha H A) Enantiotopic C) Mesotopic B) Diastereotopic D) Homotopic 20) What two groups make up the carboxylic acid group (RCOOH)? A) Carbon dioxide and hydrogen B) Carbon monoxide and hydroxyl C) Carbonyl and hydroxyl D) Carbonyl oxide and hydrogen 21) What is the correct IUPAC name of the following compound? IOH OH A) 4-Isopropyl-3-methylbutanoic acid B) 3,5-Dimethy-1-hexanoic acid C) 3,5-Dimethylhexanoic acid D) 2,4-Dimethylhexanoic acid