Suppose you are conducting research relating acid and base strength to molecular structure. You might begin by comparing compounds with known acidity and basicity constants. Decide which member of each of the following pairs is the stronger acid or base in water:

(a) Acid: HF or HIO₃;

(b) Base: NO₂^– or CN^–.

PLAN You need to compare the K_a of each weak acid. For anions, identify the conjugate weak acid and compare the K_a values.