About $.......\, \%$ impurity remains in alumina obtained by Bayer's method. (in $\%$)

$A$ metal $E$ is stored under kerosene oil. When a small piece of it is left open in the air,it catches fire. When the product formed is dissolved in water,it turns red litmus blue.
$(i)$ Name the metal $E$.
$(ii)$ Write the chemical equations for the reaction when it is exposed to air and when the product is dissolved in water.
$(iii)$ Explain the process by which the metal is obtained from its molten chloride.

What is an ore of aluminium?

What is the chemical formula of copper pyrites?

Which kind of impurities are present in the ores? What are these impurities collectively known as?

Which of the following metals is obtained in free state in nature?