Question

available: oct 1, 2025 8:30am until oct 1, 2025 10:30am
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hester, treyvon
dtal - ch - term 1 - unit 4a assessment - 25 - 26
which of the following correctly represents an ion pair and the ionic compound they form?
○ k⁺, s²⁻; ks
○ mg²⁺, br⁻; mgbr₂
○ al³⁺, o²⁻; al₂o₃
○ li⁺, n³⁻; li₃n₃

Explanation:

Step1: Recall ionic - compound formation rule

Ionic compounds are formed by the combination of cations and anions such that the overall charge of the compound is zero. The number of cations and anions is adjusted to balance the charges.

Step2: Analyze option with K⁺ and S²⁻

Potassium has a + 1 charge ($K^{+}$) and sulfur has a - 2 charge ($S^{2 -}$). To balance the charges, the formula of the ionic compound should be $K_{2}S$, not $KS$.

Step3: Analyze option with Mg²⁺ and Br⁻

Magnesium has a + 2 charge ($Mg^{2+}$) and bromine has a - 1 charge ($Br^{-}$). To balance the charges, two bromide ions are needed for one magnesium ion, and the formula of the ionic compound is $MgBr_{2}$. This option is correct.

Step4: Analyze option with Al³⁺ and O²⁻

Aluminum has a + 3 charge ($Al^{3+}$) and oxygen has a - 2 charge ($O^{2 -}$). To balance the charges, the formula of the ionic compound should be $Al_{2}O_{3}$, not $AlO$.

Step5: Analyze option with Li⁺ and N³⁻

Lithium has a + 1 charge ($Li^{+}$) and nitrogen has a - 3 charge ($N^{3 -}$). To balance the charges, the formula of the ionic compound should be $Li_{3}N$, not $LiN_{3}$.

Answer:

Mg²⁺, Br⁻; MgBr₂