Which non-metal element exists in a liquid state at room temperature?

$(a)$ List two differences between calcination and roasting in tabular form.
$(b)$ Which method will you use to reduce the following? Explain by giving a suitable example.
$(i)$ Oxides of less reactive metals.
$(ii)$ Oxides of moderately reactive metals.
$(iii)$ Oxides of highly reactive metals.

Iqbal treated a lustrous,divalent element $M$ with sodium hydroxide. He observed the formation of bubbles in the reaction mixture. He made the same observations when this element was treated with hydrochloric acid. Suggest how can he identify the produced gas. Write chemical equations for both the reactions.

Which process is used to obtain metal from metal oxide?

What is the chemical formula of sodium sulfite?

Name the ore of mercury. How is mercury extracted from its ore?