Check CBSE Class 9 Science extra questions and answers for Chapter 13 - Why Do We Fall Ill. All these questions are important from the examination point of view. These questions are helpful to revise ...

6.Calculate the number of moles of magnesium present in a magnesium ribbon weighing 12 gm. Molar atomic mass of Magnesium is 24 gm/mol. 7.Write postulates of Daltion's atomic theory (at least three).