Which of the following statement(s) is/are not correct?

Options

A. The covalency of N in `HNO_(3)` is +5
B. `HNO_(3)` in the gaseous state has a trigonal planar structure
C. The oxidation state of N in `HNO_(3)` is +4
D. Gold dissolves in `HNO_(3)` to form gold nitrate

Answer

To determine which statements about Nitric Acid (HNO3) are not correct, we will analyze each statement step by step.

### Step 1: Analyze the first statement
**Statement:** The covalency of Nitrogen in Nitric Acid is plus 5.

**Solution:**
- Covalency refers to the number of bonds an atom can form with other atoms.
- In HNO3, the nitrogen atom is bonded to three oxygen atoms: one by a double bond and two by single bonds (one of which is part of the hydroxyl group).
- Counting the bonds: Nitrogen forms 4 bonds (1 double bond and 2 single bonds).
- Therefore, the covalency of nitrogen in HNO3 is **4**, not **5**.

### Step 2: Analyze the second statement
**Statement:** Nitric Acid in the gaseous state has a triangular planar structure.

**Solution:**
- The molecular geometry of HNO3 is indeed trigonal planar due to the sp2 hybridization of nitrogen.
- This statement is **correct**.

### Step 3: Analyze the third statement
**Statement:** The oxidation state of Nitrogen in Nitric Acid is plus 4.

**Solution:**
- Let the oxidation state of nitrogen be \(X\).
- The equation based on the oxidation states is:
\[ +1 (for H) + X + 3 \times (-2) (for O) = 0 \]
\[ +1 + X - 6 = 0 \implies X - 5 = 0 \implies X = +5 \]
- Therefore, the oxidation state of nitrogen in HNO3 is **+5**, not **+4**.

### Step 4: Analyze the fourth statement
**Statement:** Gold dissolves in Nitric Acid to form Gold Nitrate.

**Solution:**
- Gold is a noble metal and does not react with nitric acid to form gold nitrate.
- Therefore, this statement is **incorrect**.

### Conclusion
The statements that are **not correct** are:
1. The covalency of Nitrogen in Nitric Acid is plus 5. (Incorrect, it is plus 4)
2. The oxidation state of Nitrogen in Nitric Acid is plus 4. (Incorrect, it is plus 5)
3. Gold dissolves in Nitric Acid to form Gold Nitrate. (Incorrect, gold does not react with nitric acid)

### Final Answer:
The statements that are not correct are **1, 3, and 4**.

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