NCERT Solutions for Class 7 Science Chapter 6: Physical and Chemical Changes

In this chapter, the reader gets to know about the two different kinds of changes, i.e., physical change and chemical change. There are various changes that we encounter around us. This chapter explains the various phenomena that we see in day-to-day life. Chemical reaction Crystallisation, Galvanization and Rusting have been discussed in great detail. Emphasis has been given on the activity part so that the concepts can be explained using everyday experiences. Students must pay attention to this chapter to understand similar changes that will be taught to them in the higher classes. The following are the points discussed in the chapter:

• Properties such as shape, size, colour, and state of a substance are called its physical properties.
• Properties such as shape, size, colour, and state of a substance are called its physical properties.
• A change in which a substance undergoes a change in its chemical properties is called a chemical change. New substances are formed.
• For rusting, the presence of both oxygen and water (or water vapour) is essential.
• The process of depositing a layer of zinc on iron is called galvanisation.
• A change in which one or more new substances are formed is called a chemical change. A chemical change is also called a chemical reaction.