In each of the following question, a statement of Assertion (A) is given followed by a corresponding statement of Reason (R). Choose the correct answer as:

Assertion (A): HClO₄ is a stronger acid than HClO₃.

Reason (R):  Oxidation state of Cl in HClO₄ is +7 and in HClO₃ it is +5.

If both assertion and reason are true, and reason is the correct explanation of the assertion.

The correct answer is option 1. If both assertion and reason are true, and reason is the correct explanation of the assertion.

Let us break down the assertion and reason provided:

Assertion (A): HClO₄ is a stronger acid than HClO₃.

This statement asserts that perchloric acid (HClO₄) is stronger as an acid compared to chloric acid (HClO₃).

Reason (R): Oxidation state of Cl in HClO₄ is +7 and in HClO₃ it is +5.

This reason points out the difference in the oxidation states of chlorine in perchloric acid (HClO₄) and chloric acid (HClO₃). In perchloric acid, chlorine has an oxidation state of +7, while in chloric acid, chlorine has an oxidation state of +5.

Explanation:

Strength of Acid: The strength of an acid is often related to its ability to donate a proton (H⁺ ion) in solution. Stronger acids readily donate protons, leading to a higher concentration of H⁺ ions in solution.

Oxidation States: The higher the oxidation state of the central atom in an oxyacid, the stronger the acid tends to be. This is because a higher oxidation state typically indicates a greater electronegativity of the central atom and, consequently, a greater tendency to donate a proton.

Comparison of HClO₄ and HClO₃: Perchloric acid (HClO₄) has chlorine in the +7 oxidation state, while chloric acid (HClO₃) has chlorine in the +5 oxidation state.

The higher oxidation state of chlorine in perchloric acid makes it more electronegative and more capable of stabilizing the negative charge of the resulting perchlorate ion (ClO₄⁻) upon donating a proton.

Therefore, perchloric acid is a stronger acid than chloric acid.

Conclusion: Both the assertion and the reason are true, and the reason explains why HClO₄ is a stronger acid than HClO₃. The higher oxidation state of chlorine in perchloric acid contributes to its greater acidity compared to chloric acid.

Thus, the correct option is: 2. If both assertion and reason are true, and reason is the correct explanation of the assertion.