NCERT Question 13 - Chapter 3 Class 10 - Metals and Non-Metals

Last updated at July 19, 2026 by

You must have seen tarnished copper vessels being cleaned with lemon or tamarind juice. Explain why these sour substances are effective in cleaning the vessels.

 

Answer:-

  • Green coating on copper is copper carbonate. It is formed by the reaction of copper with carbon dioxide , moisture and oxygen in the atmosphere.
  • Copper is a metal . Hence, it forms a basic oxide .
  • So, Copper oxide is basic in nature.
  • Lemon and tamarind juice are acidic in nature.
  • Lemon / tamarind juice reacts with the basic copper oxide to neutralise it, forming salt and water and thus cleaning them.

green coating on copper - Teachoo.png

  after cleaning with lemon - Teachoo.png

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