Question

Rusting of iron is a chemical change because:
A. It is temporary
B. It can be cleaned and the original substance recovered
C. It is a slow reaction
D. A new substance is formed

Answer 1

To solve this question, we must first understand the difference between physical change and chemical change and also must be aware of the concept of Rusting of Iron. Then we need to assess the characteristics of rusting of iron in such a way that we may conclude a correct answer among the provided options and then only we can conclude the correct answer.

Complete answer:
Before we move forward with the solution of this given question, let us first understand some basic concepts:
1.Physical changes : only change the appearance of a substance, not its chemical composition.
2.Chemical changes : cause a substance to change into an entirely substance with a new chemical formula.
3.Rusting of Iron : It refers to the formation of rust which is a mixture of iron oxides, on the surface of iron objects or structures. This rust is formed from a redox reaction between oxygen and iron in an environment containing water (or high levels of moisture). The rusting of iron is characterized by the formation of a layer of a red, flaky substance that easily crumbles into a powder.

Rusting of iron is a chemical change because it happens due to a chemical reaction between iron and air in presence of moisture. If the chemical reaction hadn’t taken place between them, the iron wouldn’t have rusted and acquired brown texture from its dull grey one. And Hence as a result a new substance is formed on the surface of Iron which is known as rust.
So, clearly we can conclude that the correct answer is, ‘D. A new substance is formed’

Note: Many types of coatings can be applied to the surface of the exposed metal in order to prevent corrosion. Common examples of coatings that prevent corrosion include paints, wax tapes, and varnish.