A wave of vibrating electric and magnetic energy
Answer: oxidizes in air
Explanation: Chemical property is the property which deals with change in chemical composition of the substance.
Physical change is the property which deals with change in physical state of the substance.

The above equation represents the oxidation of methane to form carbon dioxide and water. Thus the chemical composition has changed and is a chemical property.
Color and odor only involves no change in chemical composition.
Explanation:
Atomic Number Element Symbol
Chlorine. Cl
Argon. Ar
Potassium. K
Calcium. Ca
3 mole of O2 produce=2 iron oxide
0.5 of O2 produce=x
0.5 X 2/3
X=0.33 mole of iron oxide