Which is true about `N_(2)O_(5)`?

Options

A. It is anhydride of `HNO_(3)`
B. in solid state it exists as `NO_(2)^(+)NO_(3)^-`
C. it is structurally similar to `P_(2)O_(5)`
D. it can be prepared by heating `HNO_(3)` over `P_(2)O_(5)`

Answer

To determine which statements about \( N_2O_5 \) (dinitrogen pentoxide) are true, we will analyze each statement step by step.

### Step 1: Analyze Statement A
**Statement A:** "It is an anhydride of HNO3."

- An anhydride of an acid is a compound that, when combined with water, produces the corresponding acid.
- The reaction of \( N_2O_5 \) with water can be represented as:
\[ N_2O_5 + H_2O \rightarrow 2 HNO_3 \]
- Since the reaction produces nitric acid (\( HNO_3 \)), this statement is **true**.

### Step 2: Analyze Statement B
**Statement B:** "In solid state, it exists as \( NO_2^+ \) and \( NO_3^- \)."

- In the solid state, \( N_2O_5 \) can dissociate into nitronium ions (\( NO_2^+ \)) and nitrate ions (\( NO_3^- \)).
- This is a characteristic of its structure in the solid phase, confirming that this statement is also **true**.

### Step 3: Analyze Statement C
**Statement C:** "It is structurally similar to \( P_2O_5 \)."

- The structure of \( P_2O_5 \) (diphosphorus pentoxide) and \( N_2O_5 \) (dinitrogen pentoxide) can be compared.
- The structure of \( P_2O_5 \) involves phosphorus atoms bonded to oxygen in a different arrangement than that of \( N_2O_5 \).
- The structural differences indicate that this statement is **false**.

### Step 4: Analyze Statement D
**Statement D:** "It can be prepared by heating \( HNO_3 \) over \( P_2O_5 \)."

- Heating \( HNO_3 \) in the presence of \( P_2O_5 \) leads to the formation of water and \( N_2O_5 \).
- The reaction can be summarized as:
\[ HNO_3 + P_2O_5 \rightarrow N_2O_5 + H_2O \]
- Therefore, this statement is **true**.

### Conclusion
From our analysis:
- Statement A: True
- Statement B: True
- Statement C: False
- Statement D: True

Thus, the true statements about \( N_2O_5 \) are A, B, and D.

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