An element ' $X$ ' belongs to $3^{\;\text{rd }\;}$ period and group 16 of the Modern Periodic Table.**(a) Determine the number of valence electrons and the valency of ' $X$ '.(b) Molecular formula of the compound when ' $X$ ' reacts with hydrogen and write its electron dot structure. (c) Name the element ' $X$ ' and state whether it is metallic or non-metallic.