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: How to read oxidation state.
Oxygen is taken as $-2$ and the whole neutral molecule must add up to zero. We solve for nitrogen in each oxide.

Step 2: Do $N_2$ and $NO$.
In $N_2$ the element is free, so nitrogen is $0$. In $NO$, $x + (-2) = 0$ gives $x = +2$.

Step 3: Do $N_2O$.
Here $2x + (-2) = 0$, so $x = +1$.

Step 4: Do $NO_2$.
Now $x + 2(-2) = 0$, which gives $x = +4$. So $NO_2$ pairs with the $+4$ entry.

Step 5: Answer.
The only correct pairing offered is $(iv)\rightarrow(q)$. \[ \boxed{(iv)\rightarrow(q)} \]