Question

In the context of the nitrogen cycle in plants, identify the correct match between the nitrogen compound and the oxidation state of nitrogen

• A. (i) -- (s)
• B. (ii) -- (p)
• C. (iii) -- (r)
• D. (iv) -- (q)

Hint:

Remember common oxidation states of nitrogen: \[ N_2=0,\quad NO=+2,\quad N_2O=+1,\quad NO_2=+4 \] These are frequently used in nitrogen cycle and redox chemistry questions.

Answer 1

The Correct Option is D

Step 1: Find oxidation state of nitrogen in \(N_2\).
In elemental form, oxidation state is always zero. Therefore,
\[ N_2 \rightarrow 0 \] Thus,
\[ (i)\rightarrow (r) \] So, option (A) is incorrect.

Step 2: Find oxidation state of nitrogen in \(NO\).
Let oxidation state of nitrogen be \(x\). Oxygen has oxidation state \(-2\).
\[ x+(-2)=0 \] \[ x=+2 \] Hence,
\[ NO \rightarrow +2 \] Thus,
\[ (ii)\rightarrow (s) \] So, option (B) is incorrect.

Step 3: Find oxidation state of nitrogen in \(N_2O\).
Let oxidation state of nitrogen be \(x\).
\[ 2x+(-2)=0 \] \[ 2x=+2 \] \[ x=+1 \] Hence,
\[ N_2O \rightarrow +1 \] Thus,
\[ (iii)\rightarrow (p) \] So, option (C) is incorrect.

Step 4: Find oxidation state of nitrogen in \(NO_2\).
Let oxidation state of nitrogen be \(x\).
\[ x+2(-2)=0 \] \[ x-4=0 \] \[ x=+4 \] Hence,
\[ NO_2 \rightarrow +4 \] Thus,
\[ (iv)\rightarrow (q) \]

Step 5: Compare all matches.
The correct matching among the given options is only
\[ (iv)\rightarrow(q) \]

Step 6: Verify the option carefully.
Option (D) correctly represents
\[ NO_2 \rightarrow +4 \]

Step 7: Final conclusion.
Therefore, the correct answer is option (D).
\[ \boxed{(iv)\rightarrow(q)} \]