Match each species on the left to a description on the right. Al I2 O2 Cr
1) oxidizing agent
2) reducing agent

Explanation:

I₂ + 2 e = 2I⁻

I₂ converts itself into I⁻ by accepting electron . In this process it increases the oxidation number of element from which it takes electron . Hence it is an oxidizing agent .

Similarly O₂ is also an oxidizing agent .

O₂ + 4e = 2O⁻²

Al is a reducing agent .

Al = Al⁺³ + 3 e

Al gives 3 electrons to other element whose oxidation number is reduced . Hence it is reducing agent .

Similarly Cr is also a reducing agent .

Cr = Cr⁺³ + 3 e .