CBSE Class 10 Science 2019 · Paper 31/3/3 · Question 9

Formula of washing soda: ${\text{Na}}_2{\text{CO}}_3\cdot 10{\text{H}}_2\text{O}$ (sodium carbonate decahydrate). From baking soda: heating baking soda gives sodium carbonate, $2{\text{NaHCO}}_3\stackrel{\text{heat}}{\to }{\text{Na}}_2{\text{CO}}_3+{\text{H}}_2\text{O}+{\text{CO}}_2$; recrystallising this sodium carbonate from water gives washing soda, ${\text{Na}}_2{\text{CO}}_3+10{\text{H}}_2\text{O}⟶{\text{Na}}_2{\text{CO}}_3\cdot 10{\text{H}}_2\text{O}$. Industries (any two): glass industry, soap industry, paper industry (also the manufacture of sodium compounds such as borax).