Hi! Thank you for the opportunity to help you with your question!
For your first question, you have to recall the definition of a compound. A compound is composed of at least 2 or more elements. Does P4 have 2 or more elements? No, it is only made up of phosphorus. Therefore, P4 is not a compound. On the other hand, a molecule is made up of 2 or more atoms that are chemically bonded. It doesn't have to contain 2 or more elements. Since P4 is made of more than 2 atoms, it is considered a molecule.
For your second question, it's important to pay attention to the charges. Ga has a +3 charge, and C2H3O2 (which is acetate by the way) has a -1 charge. To balance the ionic compound and give it a net charge of zero, you need one Ga3+ molecule and three acetate molecules: there is a total positive charge of +3 and a total negative charge of -3, so they cancel. The final ionic compound is Ga3+(C2H3O2)- subscript3Please let me know if you need any clarification. I'm always happy to answer your questions!
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