An element ' $X$ ' belong to $3^{\text{rd }}$ period and group 13 of the Modern Periodic Table. (a) Determine the valence electrons and the valency of ' $X$ '.(b) Molecular formula of the compound formed when ' $X$ ' reacts with an element ' $Y$ ' (atomic number $=8$ ).(c) Write the name and formula of the compound formed when ' $\ X$ ' combines with chlorine.