Q16 of 65 Page 18

If copper is kept open in air, it slowly loses its shining brown surface and gains a green coating. It is due to the formation of

Copper gets green coating due to the formation of a mixture of copper carbonate and copper hydroxide when it reacts with carbon dioxide gas and moisture present in air. This is called tarnishing of copper.


The reactionn is as follows:
2Cu + H2O + CO2 + O2 → Cu(OH)2 + CuCO3

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Generally, metals are solid in nature. Which one of the following metals is found in liquid state at room temperature?

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Which of the following metals are obtained by electrolysis of their chlorides in molten state?

(i) Na


(ii) Ca


(iii) Fe


(iv) Cu