Which of the following metals is the most reactive?

Which of the following oxide$(s)$ of iron would be obtained on prolonged reaction of iron with steam?

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.

Food cans are coated with tin and not with zinc because

Explain why calcium metal starts floating on the surface of water after reacting with it. Write the chemical equation for the reaction.

Give one most suitable word for the following statements.
$(a)$ Metal oxides which show basic as well as acidic behaviour.
$(b)$ Iodine,a non-metal is shining.