K _a for HF Is 3

Multiple Choice

K _a for HF is 3.5×10 ^{- 4}. Calculate K _b for the fluoride ion.

A) 2.8×10³
B) 3.5×10 ^{- 4}
C) 1.0×10 ^{- 7}
D) 3.5×10 ^{- 10}
E) 2.8×10 ^{- 11}