Disproportionation reaction of KClO3

Steps:

• KClO3 decomposes to KClO4 and KCl in 4:3:1 ratio, yielding two Cl compounds (KClO4:KCl = 3:1).
• In KClO3, Cl oxidation number is +5 (calculated as +5 for Cl in K(+1)ClO3 with O(-2)).
• In products, Cl in KClO4 is +7 (K(+1)ClO4, 4O(-2) = -8, so Cl +7); in KCl, Cl is -1.
• Cl changes from +5 to +7 and -1, with no other elements changing oxidation states.

Why C is correct:

• Matches the reaction 4KClO3 → 3KClO4 + KCl, where Cl oxidizes to +7 and reduces to -1, conserving charge and ratio.

Why the others are wrong:

• A: +3 not produced; no Cl compound with +3 in this decomposition.
• B: +6 and +4 not formed; reaction yields only +7 and -1 for Cl.
• D: +1 not possible; Cl in compounds here is either perchlorate (+7) or chloride (-1).

Final answer: C