When an object made of metal A is kept in air for a considerable time, it loses its shine and becomes almost black due to the formation fo a layer of substance B. when an object made of another metal C is kept in damp air for a considerable time, it gets covered with a green layer of substance D. Metal A is the best conductor of electricity whereas metal C is the next best conductor of electricity.
(a) What is metal A?
(b) What is metal C?
(c) name the substance B.
(d) name the substance D.
(e) What type of chemcial can be used to remove the green layer from metal C and clean it? Why?

Explanation

(a) Silver (b) copper (c) silver sulphide (d0 Basic copper carbonate (e) dilute acid solution, The acid solution dissolves green coloured basic copper carbonate present on the corroded copper object