Which non-metal element possesses luster?

What is the percentage of $H_{2}SO_{4}$ in dilute sulfuric acid (in $\%$)?

Metals are refined by using different methods. Which of the following metals are refined by electrolytic refining?
$(i)$ $Au$
$(ii)$ $Cu$
$(iii)$ $Na$
$(iv)$ $K$

Generally,in what forms are the elements present in the lithosphere?

Give the steps involved in the extraction of metals of low and medium reactivity from their respective sulphide ores.

In the $Hall-Heroult$ process,which substances are added to alumina to lower its melting point?