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 .

definition

                    entropy is a measure of the randomness or the extent of disorder of a chemical process.

                      enthalpy is a measure of the heat change of a reaction occurring at a constant pressure.

measurement units:

                        entropy is measured in joule per kelvin (jk⁻¹)   whereas enthalpy is measured in joule per mole (jmol⁻¹)

requirements:

                            entropy has no requirements or limits, and its change is measured by the division between the heat change of the chemical process and the temperature.

                              in contrast, enthalpy can only be related to the heat change of the reaction under standard conditions.