Cr + 3fe3+cr3+ + 3fe2+ in the above redox reaction, use oxidation numbers to identify the element oxidized, the element reduced, the oxidizing agent and the reducing agent.

Element Cr goes from Cr --> Cr³⁺
element Fe goes from Fe³⁺ --> Fe²⁺
oxidation reactions are when the species gives out electrons and its oxidation number increases.
reduction reactions are when the species take in electrons and its oxidation number reduces.
Cr : oxidation number of Cr - 0 and Cr³⁺ - +3
Theres an increase in oxidation number from 0 to +3. Therefore its an oxidation reaction. Cr gets oxidised. 
Fe : oxidation number of Fe³⁺ - +3 and Fe²⁺ - +2
There's a decrease in oxidation number of Fe from +3 to +2, therefore its a reduction reaction and Fe gets reduced.
         
Cr reduces Fe - Cr is the reducing agent 
Fe oxidises Cr - Fe is the oxidising agent

Non metal is an element or substance that is not a metal metal is a solid material that is typically hard, shiny, malleable, fusible, and ductile, with good electrical and thermal conductivitymetalloid is an element (e.g., germanium or silicon) whose properties are intermediate between those of metals and solid nonmetals. they are electrical semiconductors.

Deposition is the transition of matter going from gas to solid without passing through the liquid phase.a.) gas—-> solid