Which of the following is the weakest acid?

Correct option is A

Correct Answer: A. HF (Hydrofluoric Acid)

• Acid strength depends on the ability to donate H⁺ ions in solution.

• Among the given acids:

  • HF is a weak acid because:

    • The H–F bond is very strong due to high bond dissociation energy.

    • Fluoride ion (F⁻) strongly holds onto its proton, so HF partially ionizes in water.

  • HCl, HNO₃, and H₂SO₄ are strong acids:

    • They completely ionize in aqueous solution.

    • H₂SO₄ is a strong acid with two ionizable protons.

• HF is dangerous due to its high reactivity with glass and tissue, but it is a weak acid in aqueous solution.

• HCl (Hydrochloric acid) is a strong acid, commonly used in labs.

• HNO₃ (Nitric acid) is a strong oxidizing acid.

• H₂SO₄ (Sulfuric acid) is a strong acid and dehydrating agent, used industrially.

• Acid strength also depends on bond polarity and stability of conjugate base.