Which alloy is composed of copper and zinc?

Which of the following methods is $NOT$ used for the concentration of an ore?

What is the process of extracting a metal from its ore and obtaining it in a pure form called?

Malachite is an ore of which metal?

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.

What are the constituent elements of brass?