Which medicine is prepared using ammonia?

What is German silver?

Name the following:
$(a)$ $A$ metal which is preserved in kerosene.
$(b)$ $A$ lustrous coloured non-metal.
$(c)$ $A$ metal which can melt while kept on palm.
$(d)$ $A$ metal which is a poor conductor of heat.

$(i)$ Given below are the steps for the extraction of copper from its ore. Write the reactions involved:
$(a)$ Roasting of copper $(I)$ sulphide
$(b)$ Reduction of copper $(I)$ oxide with copper $(I)$ sulphide
$(c)$ Electrolytic refining
$(ii)$ Draw a neat and well-labelled diagram for the electrolytic refining of copper.

What is the chemical formula of oleum?

Give the composition of the alloys brass and bronze.