Which method is used for the purification of semiconductor metals?

Which salts are formed when sulfuric acid reacts with metals?

Galvanisation is a method of protecting:

Who discovered the method for the industrial production of ammonia?

Which metal is stored in kerosene?

$(a)$ Write the chemical name of the coating that forms on silver and copper articles when these are left exposed to moist air.
$(b)$ Explain what is galvanisation? What purpose is served by it?
$(c)$ Define an alloy. How are alloys prepared? How do the properties of iron change when:
$(i)$ small quantity of carbon,
$(ii)$ nickel and chromium are mixed with it.