Question

given the following mystery ions, $x^{3 +}$, $m^{2 -}$, $q^{2+}$, $j^{-}$. which formula would not be correct for an ionic compound?

Explanation:

Step1: Recall ionic - compound formation rule

Ionic compounds are formed by the combination of cations (positively - charged ions) and anions (negatively - charged ions) such that the overall charge of the compound is zero.

Step2: Analyze possible combinations

For $X^{3 +}$ and $M^{2-}$, the formula of the ionic compound is $X_2M_3$ because to balance the charges, we need 2 $X^{3+}$ ions ($2\times( + 3)=+6$) and 3 $M^{2 -}$ ions ($3\times(-2)= - 6$).
For $Q^{2+}$ and $J^-$, the formula of the ionic compound is $QJ_2$ because we need 2 $J^-$ ions to balance the + 2 charge of one $Q^{2+}$ ion.
For $X^{3+}$ and $J^-$, the formula of the ionic compound is $XJ_3$ because we need 3 $J^-$ ions to balance the + 3 charge of one $X^{3+}$ ion.
For $Q^{2+}$ and $M^{2-}$, the formula of the ionic compound is $QM$ since the + 2 charge of $Q^{2+}$ is balanced by the - 2 charge of $M^{2-}$.

Answer:

Any formula that does not follow the charge - balancing rule for ionic compounds would be incorrect. Without specific incorrect formulas given as options, we can't choose a particular answer from a list. But in general, something like $XJ$ for $X^{3+}$ and $J^-$ (without balancing the charges) would be incorrect. If we assume options were provided, we would check each one against the charge - balancing principle.