Name a non-metal which is lustrous and a metal which is non-lustrous.

What happens when carbon dioxide is dissolved in water at high pressure?

An element $A$ is soft and can be cut with a knife. It is very reactive to air and cannot be kept open in air. It reacts vigorously with water. Identify the element from the following:

$(a)$ 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.

Out of the $114$ elements discovered so far,how many elements do not behave as metals?

Name the metal which:
$(a)$ becomes blackish after a certain time.
$(b)$ develops a green coating on exposure to air.
$(c)$ does not corrode at all.
$(d)$ is used in making steel.
$(e)$ is non-lustrous.