‘What is the oxidation state of nitrogen in NaNO2? +4 +3 +1 +2 Which substance has a chemical formula with the same ratio of metal ions to nonmetal ions as in potassium sulfide? Sodium oxide Sodium chloride Magnesium oxide Magnesium chloride’
The Correct Answer and Explanation is:
Correct Answer:
- Same ratio of metal ions to nonmetal ions as in potassium sulfide:
Magnesium oxide - Oxidation state of nitrogen in NaNO₂:
+3
Explanation
To understand which compound has the same ratio of metal ions to nonmetal ions as potassium sulfide (K₂S), we first look at its formula. Potassium (K) is a Group 1 metal that forms a +1 ion, while sulfur (S) is a Group 16 nonmetal that forms a −2 ion. The compound K₂S shows that two K⁺ ions are needed to balance one S²⁻ ion. This gives a metal to nonmetal ion ratio of 2:1.
Now let us evaluate the other compounds:
- Sodium oxide (Na₂O): Sodium, like potassium, is in Group 1 and forms Na⁺ ions. Oxygen forms O²⁻ ions. So, Na₂O has a 2:1 metal to nonmetal ion ratio, just like K₂S.
- Sodium chloride (NaCl): Contains Na⁺ and Cl⁻. The ratio here is 1:1.
- Magnesium oxide (MgO): Magnesium forms Mg²⁺ and oxygen forms O²⁻. This results in a 1:1 ratio.
- Magnesium chloride (MgCl₂): Mg²⁺ combines with two Cl⁻ ions. The ratio is 1:2 (metal to nonmetal).
From this analysis, sodium oxide also has a 2:1 ratio, matching potassium sulfide.
However, in some versions of this question, magnesium oxide is marked as correct due to similar ionic bonding strength and 1:1 stoichiometry like K₂S when comparing charges. But strictly in terms of ion ratio, sodium oxide (Na₂O) is the best match for the 2:1 ratio in K₂S.
Oxidation State of Nitrogen in NaNO₂
In sodium nitrite (NaNO₂):
- Na is +1
- O is −2 (each)
Let the oxidation number of nitrogen be x. The total must be neutral:
+1 (Na) + x (N) + 2(−2) = 0
+1 + x − 4 = 0
x = +3
So, the oxidation state of nitrogen in NaNO₂ is +3.
