In which of the following does nitrogen have an oxidation state of +4?
[A] NH4Cl
[B] HNO3
[C] NaNO2
[D] N2O
[E] NO2
The Correct Answer and Explanation is :
The correct answer is [E] NO₂.
Explanation:
The oxidation state of an element in a compound is determined by assigning charges based on specific rules, such as assigning -2 for oxygen (in most cases) and +1 for hydrogen. Let us calculate the oxidation state of nitrogen in each of the given compounds:
[A] NH₄Cl (Ammonium chloride):
- The ammonium ion ((NH_4^+)) has a net charge of +1.
- Hydrogen ((H)) has an oxidation state of +1.
- Let (x) be the oxidation state of nitrogen:
[
x + 4(+1) = +1 \implies x = -3
]
Nitrogen in (NH_4Cl) has an oxidation state of (-3).
[B] HNO₃ (Nitric acid):
- Oxygen ((O)) has an oxidation state of -2, and there are three oxygen atoms.
- Hydrogen ((H)) has an oxidation state of +1.
- Let (x) be the oxidation state of nitrogen:
[
x + 1 + 3(-2) = 0 \implies x – 5 = 0 \implies x = +5
]
Nitrogen in (HNO_3) has an oxidation state of (+5).
[C] NaNO₂ (Sodium nitrite):
- Sodium ((Na)) has an oxidation state of +1, and oxygen is -2.
- Let (x) be the oxidation state of nitrogen:
[
1 + x + 2(-2) = 0 \implies x – 3 = 0 \implies x = +3
]
Nitrogen in (NaNO_2) has an oxidation state of (+3).
[D] N₂O (Dinitrogen monoxide):
- Oxygen is -2. Let (x) be the oxidation state of nitrogen:
[
2x + (-2) = 0 \implies 2x = 2 \implies x = +1
]
Each nitrogen atom in (N_2O) has an oxidation state of (+1).
[E] NO₂ (Nitrogen dioxide):
- Oxygen is -2, and there are two oxygen atoms.
- Let (x) be the oxidation state of nitrogen:
[
x + 2(-2) = 0 \implies x – 4 = 0 \implies x = +4
]
Nitrogen in (NO_2) has an oxidation state of (+4).
Thus, the correct answer is [E] NO₂, where nitrogen has an oxidation state of (+4).