The compound made from europium and chloride ions would be EuCl3, as europium forms a 3+ cation and chloride ions carry a 1- charge, thus three chloride ions would need to bond with one europium ion to maintain charge neutrality.
The question is asking for the formula of the compound made from europium and chloride ions. Europium is a metal that forms a 3+ cation (Eu³⁺), while chloride ions carry a single negative charge (Cl⁻). As ions must combine in a way that the total charge of the compound is neutral, three chloride ions would need to bond with a single europium ion. Thus, the formula of the compound would be EuCl3, corresponding to Option 4: EuCl3.
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