Question

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Answer 1

Q22. The coatings were seen due to corrosion of metal

Copper(Cu)+Carbon Dioxide(CO2)+H2O=Copper Carbonate(CuCCO3.nH2O)

Silver+ Hydrogen Sulphide=Silver Sulphide (Ag2S)+Hydrogen(H2)

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Answer 2

22) since the silver and copper coins are exposed to the moisture corrosion occurs making them tarnished that is black and green   wen silver is exposed it gets tarnished because the atmosphere contains some amount of hydrogen sulphide and forms a black coating of silver sulphide   Copper forms a green deposit on surface when exposed to moist air it is a mixture of copper hydroxide and copper carbonate collectively called basic copper carbonate .[2CuCo3.Cu(OH)2]  Hope it helps  Plzzzzz mark me as brainliest