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Copper reacts with moist gas 'A' present in the air and slowly loses its shiny surface. It turns green. Identify 'A' and the substance of green coating formed on the surface of copper.
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The slow and gradual degradation of metals due to their reaction with moisture, acids etc. present in the atmosphere is called corrosion. (1 Mark)
Silver articles react with sulphur in the air to form a coating of silver sulphide, which is black in colour. (1 Mark)
A – Carbon dioxide/ $\ce{CO2}$ (1 Mark)
Green coating is of copper carbonate/ $\ce{CuCO3}$ (1 Mark)
OR
An alloy is a homogenous mixture of two or more metals, or a metal and a non-metal. (1 Mark)
It is made by mixing the metals in molten state. (1 Mark)
Silver articles react with sulphur in the air to form a coating of silver sulphide, which is black in colour. (1 Mark)
A – Carbon dioxide/ $\ce{CO2}$ (1 Mark)
Green coating is of copper carbonate/ $\ce{CuCO3}$ (1 Mark)
OR
An alloy is a homogenous mixture of two or more metals, or a metal and a non-metal. (1 Mark)
It is made by mixing the metals in molten state. (1 Mark)