Oxidation number changes for N and S in the reaction

Steps:

• Calculate N in HNO₃: H (+1) + N + 3O (-6) = 0, so N = +5.
• Calculate N in NO: N + O (-2) = 0, so N = +2; change = +2 - (+5) = -3.
• Calculate S in SO₂: S + 2O (-4) = 0, so S = +4.
• Calculate S in HSO₄⁻: H (+1) + S + 4O (-8) = -1, so S = +6; change = +6 - (+4) = +2.

Why none is correct:

• Changes are N -3 (reduction by 3e⁻), S +2 (oxidation by 2e⁻), per standard oxidation number rules; no option matches.

Why the others are wrong:

• A: S change +3 incorrect (actual +2 from +4 to +6).
• B: N change -2 incorrect (actual -3 from +5 to +2).
• C: Both N -2 and S +3 incorrect.
• D: N change -1 incorrect (actual -3).

Final answer: None of the options