Q. 123.9( 17 Votes )
A student has found black coating on his silver coins and green coating on his copper coins. Which chemical phenomenon is responsible for this? Write chemical name of these coatings.
The chemical phenomenon which is responsible is corrosion.
When a metal is attacked by substances around it such as moisture, acids, etc. it is said to corrode and this process is called corrosion.
After corrosion, the colour of:
Silver changes to → black
Copper changes to → green
Hence, the chemical name of coatings are silver coating and copper coating.
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Which among the following statement(s) is(are) true? Exposure of silver chloride to sunlight for a long duration turns grey due to:
(i) The formation of silver by decomposition of silver chloride
(ii) Sublimation of silver chloride
(iii) Decomposition of chlorine gas from silver chloride
(iv) Oxidation of silver chlorideEvergreen Science
Which of the following are exothermic processes?
(i) Reaction of water with quicklime
(ii) Dilution of an acid
(iii) Evaporation of water
(iv) Sublimation of camphor (crystals)Evergreen Science