By which method is aluminum metal obtained by the reduction of alumina?

Which of the following substances is hygroscopic?

What is the proportion of gold and copper in $22$ carat gold ornaments?

In which state does the element phosphorus exist at room temperature?

$(a)$ Carbon cannot be used as a reducing agent to obtain $Mg$ from $MgO$. Why?
$(b)$ How is sodium obtained from molten sodium chloride? Give the equations of the reactions.
$(c)$ How is copper obtained from its sulphide ore? Give the equations of the reactions.

Which of the following metals exist in their native state in nature?
$(i)$ $Cu$
$(ii)$ $Au$
$(iii)$ $Zn$
$(iv)$ $Ag$