Class 7: Science Chapter 18 solutions. Complete Class 7 Science Chapter 18 Notes. NCERT Solutions for 7th Class Science: Chapter 18-Watsewater Story NCERT 7th Science Chapter 18, class 7 Science Chapter 18 solutions Exercise 1. Fill in the blanks: (a) Cleaning of water is a process of removing ____________. (b) Wastewater released by houses is […]