Answer: A₃B₂
Step-by-step explanation:
In a chemical formula the subscripts indicate the number of atoms or ions of each element, so in the formula A₃B₂, the subscript 3 indicates that the unit formula has three ions of element A, and the subscript 2 indicates 2 ions of the element B. Hence, the ratio A to B is 3 : 2.
You check the correctness of the unit formula by adding the total charges knowing that the final net charge of a neutral compound is zero. This table shows the balance of the charges for the compound A₃B₂:
Ion Charge Number of ions Total charge
(each ion) (subscript in the formula) (# ions × charge per ion)
A +2 3 +2 × 3 = +6
B -3 2 -3 × 2 = - 6
Net charge: +6 - 6 = 0