Answer : The formula unit of Sr & Cl is [tex]SrCl_2[/tex] and the formula unit of Al & S is [tex]Al_2S_3[/tex]
Explanation :
Formula unit : it is defined as the lowest number ratio of ions of an elements in an ionic compound or covalent compound.
For the formula unit of Sr & Cl, two chloride ions[tex](Cl^-)[/tex] are needed to neutralize the one strontium ion[tex](Sr^{2+})[/tex].
For the formula unit of Al & S, three sulfide ions[tex](S^{2-})[/tex] are needed to neutralize the two aluminium ion[tex](Al^{3+})[/tex].
The formula unit of [tex]SrCl_2[/tex] and [tex]Al_2S_3[/tex] are shown below.
