What is German silver?

Give reasons for the following:
$(i)$ Most metals conduct electricity well.
$(ii)$ The reaction of iron $(III)$ oxide,$Fe_{2}O_{3}$,with heated aluminium is used to join cracked machine parts.
$(iii)$ Sodium,potassium,and lithium are stored under oil.

Which of the following is not an oxide of metal?

Give reasons for the following:
$(a)$ We can store copper sulphate solution in a silver vessel but not silver nitrate solution in a copper vessel.
$(b)$ The reaction of zinc with dilute nitric acid does not produce hydrogen gas.
$(c)$ Food cans are coated with tin rather than zinc.

Give reasons for the following:
$(i)$ Alloys are used in electrical heating devices rather than pure metals.
$(ii)$ Gold ornaments look new even after several years of use.
$(iii)$ An iron grill should be painted frequently.

Which one of the following figures correctly describes the process of electrolytic refining?