In which species does nitrogen have the highest oxidation number

In which species does nitrogen have the highest oxidation number?

A) HNO2

B) N2

C) NH3

D) NaNO3

E) NO2

The correct answer and explanation is :

The correct answer is D) NaNO₃.

Explanation:

Oxidation numbers represent the charge an atom would have if all bonds were completely ionic. The oxidation number of nitrogen varies widely because nitrogen can form compounds with multiple oxidation states, ranging from -3 (e.g., NH₃) to +5 (e.g., nitrates).

Let’s determine the oxidation numbers of nitrogen in each compound:

1. HNO₂ (Nitrous acid)

• Hydrogen (H) has an oxidation number of +1.
• Oxygen (O) typically has an oxidation number of -2.
• Let the oxidation number of nitrogen be x.
• The sum of oxidation numbers in a neutral molecule is 0:
  [
  +1 + x + 2(-2) = 0
  ]
  [
  x – 3 = 0 \Rightarrow x = +3
  ]
• Oxidation number of N = +3.

1. N₂ (Diatomic nitrogen)

• Elemental nitrogen is in its natural state, so its oxidation number is 0.

1. NH₃ (Ammonia)

• Hydrogen has an oxidation number of +1.
• Let nitrogen be x.
• The sum of oxidation numbers in a neutral molecule is 0:
  [
  x + 3(+1) = 0
  ]
  [
  x + 3 = 0 \Rightarrow x = -3
  ]
• Oxidation number of N = -3.

1. NaNO₃ (Sodium nitrate)

• Sodium (Na) is in Group 1, so it has an oxidation number of +1.
• Oxygen is -2, and there are three oxygens, contributing -6 in total.
• Let nitrogen be x:
  [
  +1 + x + 3(-2) = 0
  ]
  [
  x – 5 = 0 \Rightarrow x = +5
  ]
• Oxidation number of N = +5.

1. NO₂ (Nitrogen dioxide)

• Oxygen is -2, and there are two oxygens, contributing -4 in total.
• Let nitrogen be x:
  [
  x + 2(-2) = 0
  ]
  [
  x – 4 = 0 \Rightarrow x = +4
  ]
• Oxidation number of N = +4.

Conclusion:

The highest oxidation number occurs in NaNO₃, where nitrogen has an oxidation state of +5.