Which of these pairs of elements is most likely to be found together in a common polyatomic ion?

• A. Magnesium and Sulfur
• B. Nitrogen and Oxygen
• C. Sodium and Chlorine
• D. Potassium and Bromine

Answer: (B)

Verified step by step guidance

1. Step 1: Understand what a polyatomic ion is — it is a charged species composed of two or more atoms covalently bonded, that together carry a net charge.
2. Step 2: Recognize that polyatomic ions typically consist of nonmetals bonded to each other, often involving elements like nitrogen, oxygen, sulfur, and phosphorus.
3. Step 3: Analyze each pair: Magnesium and Sulfur are a metal and a nonmetal, which usually form ionic compounds rather than polyatomic ions.
4. Step 4: Sodium and Chlorine, as well as Potassium and Bromine, are pairs of metals and halogens that form simple ionic salts, not polyatomic ions.
5. Step 5: Nitrogen and Oxygen are both nonmetals and commonly combine to form well-known polyatomic ions such as nitrate (\(\mathrm{NO_3^-}\)) and nitrite (\(\mathrm{NO_2^-}\)), making them the most likely pair to be found together in a common polyatomic ion.