Question

Which of the following is the strongest acid ?

• A. H₂SO₃
• B. H₂SO₄
• C. HClO₄
• D. H₃PO₄

Answer 1

Answer: (C)

The explanation for the correct option:

Option(C) HClO₄

• It is a $HCl{O}_4$
• For oxy acids, we decide the strength of the acids by the oxidation state of the central atom.
• The greater the oxidation state greater its strength.
• In $HCl{O}_4$ the oxidation state of chlorine which is the central atom is +7.

The explanation for the incorrect option:

(A) $H_{2}S{O}_3$ - In this molecule, sulfur is the central atom, its oxidation state is +4

(B) $H_{2}S{O}_4$ - In this molecule, sulfur is the central atom, its oxidation state is +6

(D) $H_{3}P{O}_4$ - In this molecule, phosphorous is the central atom, and its oxidation state is +5.

Hence, Option(C)$HCl{O}_4$ is the strongest acid.