Unit 4

This chapter discusses the various uses of water and lists the different water sources. We learn that water is necessary for the survival of all living beings. It also explains the water cycle and the need to conserve water.

This chapter discusses the concept of air and its composition. We will learn about the importance of air for human beings. It explains how oxygen and carbon dioxide maintain the balance in nature. It also describes various uses of air.

This chapter describes how to reuse, reduce, and recycle different wastes. It explains the various methods of recycling biodegradable wastes and waste disposal methods. It also lists the advantages and limitations of using plastics.