What is the name of the apparatus used for the electrolysis of pure water?

Which one of the following metals does not react with cold as well as hot water?

An alkali metal $A$ gives a compound $B$ (molecular mass $= 40$) on reacting with water. The compound $B$ gives a soluble compound $C$ on treatment with aluminium oxide. Identify $A$,$B$ and $C$ and give the reaction involved.

Aluminium is used for making cooking utensils. Which of the following properties of aluminium are responsible for the same?
$(i)$ Good thermal conductivity
$(ii)$ Good electrical conductivity
$(iii)$ Ductility
$(iv)$ High melting point

Which substance is formed when ammonia gas reacts with hydrogen chloride gas?

State whether the following statement is true or false:
At ordinary temperature,the surfaces of metals such as magnesium,aluminium,zinc,lead,etc.,are covered with a thin layer of oxide which prevents the metal from further oxidation.