Which of the following metals is the most reactive?

$(a)$ 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.

Differentiate between roasting and calcination and give examples.

Which of the following is a compound of hydrogen and oxygen?

Which of the following oxide$(s)$ of iron would be obtained on prolonged reaction of iron with steam?

$(i)$ Define the term 'anode mud'. Name the electrode made of pure metal.
$(ii)$ Give the reactions taking place at cathode and at anode during the electrolytic refining of copper.