Weak acids ionize partially in solution

Steps:

• Recall that acids are classified as strong or weak based on ionization in water.
• Strong acids fully dissociate, producing many H⁺ ions; weak acids do not.
• Ethanoic acid (CH₃COOH) partially ionizes: CH₃COOH ⇌ CH₃COO⁻ + H⁺.
• This partial dissociation defines it as weak, unlike strong acids like HCl.

Why C is correct:

• Weak acids are defined by low dissociation in water, with equilibrium constant K_a < 1, leading to few ions.

Why the others are wrong:

• A: Being organic does not determine strength; some organic acids are strong.
• B: Poor conductivity results from low ionization, but it's not the definition of weakness.
• D: Reaction with metals depends on acid strength but is not the core reason for classification.

Final answer: C