Brass is an alloy of

By which method/process is sulphur obtained from the earth's crust?

Which of the following is a reducing agent?

What is the typical carat value of gold used in jewelry?

Solder is an alloy of lead and tin. It has a:

From amongst the metals sodium,calcium,aluminium,copper and magnesium,name the metal:
$(i)$ which reacts with water only on boiling,and
$(ii)$ another which does not react even with steam.