Question

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 of 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.

What type of chemical can be used to remove the green layer from metal C and clean it ? Why ?

Answer 1

(a) Silver

(b) Copper

(c) Silver sulphide

(d) Basic copper carbonate

(e) Dilute acid solution; The acid sol ution dissolves green coloured basic copper carbonate present on the corroded copper object makes it look shiny, red brown again.