Classify the following as chemical or physical changes:

  • Cutting of trees – Physical Change (The tree is chopped into smaller pieces, but the wood itself doesn’t change composition)
  • Melting of butter in a pan – Physical Change (Butter changes state from solid to liquid, but the fat molecules remain the same)
  • Rusting of almirah – Chemical Change (Iron in the almirah reacts with oxygen to form a new substance, rust)
  • Boiling of water to form steam – Physical Change (Water changes state from liquid to gas, but the H2O molecules remain unchanged)
  • Passing of electric current through water and the water breaking down into hydrogen and oxygen gases – Chemical Change (Electrical energy breaks the bonds between hydrogen and oxygen atoms, forming entirely new substances)
  • Dissolving common salt in water – Physical Change (Salt crystals separate into individual ions, but the chemical composition of the salt (NaCl) stays the same)
  • Making a fruit salad with raw fruits – Physical Change (Fruits are mixed together, but their chemical makeup remains unchanged)
  • Burning of paper and wood – Chemical Change (Paper and wood react with oxygen, releasing heat and light and forming new substances like ash and smoke)