Gclo3- + fe2++ 2h+clo2 + fe3++ h2o in the above redox reaction, use oxidation numbers to identify the element oxidized, the element reduced, the oxidizing agent and the reducing agent.

Cl element reduced

ClO₃⁻ oxidizing agent

Fe element oxidized

Fe²⁺ reducing agent

Explanation:

Let's consider the following redox reaction.

ClO₃⁻ + Fe²⁺ +  2 H⁺ ⇄ ClO₂ + Fe³⁺ + H₂O

Cl has the oxidation number (o.n.) +5 in ClO₃⁻ and +4 in ClO₂, so Cl is the element reduced according to the following reduction half-reaction.

2 H⁺ + ClO₃⁻ + 1 e⁻ ⇒ ClO₂ + H₂O

As a consequence, ClO₃⁻ is the oxidizing agent.

Fe has the o.n. +2 in Fe²⁺ and +3 in Fe³⁺, so Fe is the element oxidized according to the following oxidation half-reaction.

Fe²⁺ ⇒ Fe³⁺ + 1 e⁻

As a consequence, Fe²⁺ is the reducing agent.