Predict the formulas of the stable binary compounds that would be formed by the combination of the following pairs of elements.
$(a)$ Lithium and oxygen
$(b)$ Magnesium and nitrogen
$(c)$ Aluminium and iodine
$(d)$ Silicon and oxygen
$(e)$ Phosphorus and fluorine
$(f)$ Element $71$ and fluorine

(A) Lithium $(Li)$ is in group-$1$ (valency $1$) and oxygen $(O)$ is in group-$16$ (valency $2$). The compound is $Li_{2}O$.
$(b)$ Magnesium $(Mg)$ is in group-$2$ (valency $2$) and nitrogen $(N)$ is in group-$15$ (valency $3$). The compound is $Mg_{3}N_{2}$.
$(c)$ Aluminium $(Al)$ is in group-$13$ (valency $3$) and iodine $(I)$ is in group-$17$ (valency $1$). The compound is $AlI_{3}$.
$(d)$ Silicon $(Si)$ is in group-$14$ (valency $4$) and oxygen $(O)$ is in group-$16$ (valency $2$). The compound is $SiO_{2}$.
$(e)$ Phosphorus $(P)$ is in group-$15$ (valency $5$) and fluorine $(F)$ is in group-$17$ (valency $1$). The compound is $PF_{5}$.
$(f)$ Element $71$ is Lutetium $(Lu)$,a lanthanoid with a stable oxidation state of $+3$. Fluorine $(F)$ has a valency of $1$. The compound is $LuF_{3}$.