Title 3. How things change & react with one another.pdf ✅

(a) Stretching rubber band (b) Chewing of food (c) Putting an electric switch on and off (d) Breaking a stick (e) Tearing clothes (f) Ploughing a farm (g) Sawing wood etc. (h) Melting of ice-cream etc. (i) Dissolution of resin in alcohol (j) Formation of dew, hail, snow, frost, mist and fog (k) Evaporation of water from sea, river lake etc  Chemical symbols of some familiar chemical elements Element Symbol 1. Potassium K 2. Barium Ba 3. Calcium Ca 4. Sodium Na 5. Magnesium Mg 6. Aluminium Al 7. Zinc Zn 8. Iron Fe 9. Nickel Ni 10. Tin Sn 11. Lead Pb 12. Hydrogen H 13. Copper Cu 14. Mercury Hg 15. Silver Ag 16. Platinum Pt 17. Gold Au 18. Fluorine F 19. Chlorine Cl 20. Iodine I 21. Oxygen O 22. Hydrogen H 23. Sulphur S 24. Carbon C 25. Helium He  Chemical formulae of some familiar chemical compounds: Compound Chemical Formulae 1. Water H2O 2. Carbon dioxide CO2 3. Hydrochloric acid HCl 4. Sulphuric acid H2SO4 5. Nitric acid HNO3 6. Carbonic acid H2CO3 7. Phosphoric acid H3PO4 8. Sodium Oxide Na2O 9. Sodium Chloride NaCl 10. Sodium sulphate Na2SO4 11. Sodium carbonate Na2CO3 12. Sodium hydroxide NaOH 13. Sodium nitrate NaNO3 14. Magnesium Oxide MgO 15. Magnesium Chloride MgCl2 16. Magnesium sulphate MgSO4 17. Magnesium Carbonate MgCO3 18. Magnesium hydroxide Mg(OH)2 19. Magnesium nitrate Mg(NO3)2 20. Calcium oxide CaO 21. Calcium chloride CaCl2 22. Calcium sulphate CaSO4 23. Calcium carbonate CaCO3 24. Calcium hydroxide Ca(OH)2 25. Zinc oxide ZnO 26. Zinc Chloride ZnCl2 27. Zinc sulphate ZnSO4 28. Zinc carbonate ZnCO3