Problem 5-48 Assign R or S configurations to the chirality centers in ascorbic acid (vitamin C). OH H OH HO CH2OH Ascorbic acid O H Problem 5-49 Assign R or S stereochemistry to the chirality centers in the following Newman projections: H Cl H CH3 H3C. OH H3C (a) H H H3C (b) CH3 H Problem 5-52 Draw the meso form of each of the following molecules, and indicate the plane of symmetry in each: OH OH (a) CH3CHCH2CH2CHCH3 CH3 H3C. -OH (c) H3C CH3 (b) Problem 5-66 Assign R or S configurations to the chiral centers in cephalexin, trade-named Keflex, the most widely prescribed antibiotic in the United States. H2N H IHH S Cephalexin N. CH3 CO₂H

Steps and explanationn please.

Steps and explanationn please.