The Following Equilibrium Is Established in Water Solution

Multiple Choice

The following equilibrium is established in water solution:
HCOOH + H₂O→HCOO ^- + H₃O⁺ K _a = 1.8×10 ^{- 4} Which of the following is false?

A) HCOO ^- is the conjugate acid of HCOOH.
B) H₂O is the conjugate base of H₃O⁺.
C) HCOOH is a weak acid.
D) H₂O is a weak base.
E) Hydroxide concentration is negligible with respect to hydrogen ion concentration.