Which of the following is/are incorrect statement (s):
(I) `CHCl_(3)` is less acidic than `CHF_(3)`
(II) Dipole moment of chlorobenzene is more than chlorocyclohexane
(III) Dipole moment of fluoromethane is more than chloromethane
(IV) `NH_(2)NH_(2).HCl` show positive test for nitrogen in lassaigne's test
(V) Dipole moment of difluoromethane is more than dichloromethane,

Options

A. I only
B. II only
C. I,II,III only
D. I,II,III,IV and V

Explanation

To determine which of the statements are incorrect, let's analyze each statement one by one.

### Step 1: Analyze Statement I
**Statement I:** `CHCl3` is less acidic than `CHF3`.

- **Analysis:**
- Chloroform (`CHCl3`) and fluoroform (`CHF3`) can lose a proton (H⁺) to form their respective anions: `CCl3⁻` and `CF3⁻`.
- The stability of the anions determines the acidity.
- `CCl3⁻` is more stable than `CF3⁻` due to the larger size and lower electronegativity of chlorine compared to fluorine, which allows better dispersal of negative charge.
- Thus, `CHCl3` is more acidic than `CHF3`, making this statement **incorrect**.

### Step 2: Analyze Statement II
**Statement II:** Dipole moment of chlorobenzene is more than chlorocyclohexane.

- **Analysis:**
- Chlorobenzene has resonance stabilization, which reduces the dipole moment compared to chlorocyclohexane.
- In chlorobenzene, the resonance causes the C-Cl bond to have a shorter bond length, which reduces the dipole moment.
- Therefore, the dipole moment of chlorobenzene is **less** than that of chlorocyclohexane, making this statement **incorrect**.

### Step 3: Analyze Statement III
**Statement III:** Dipole moment of fluoromethane is more than chloromethane.

- **Analysis:**
- The dipole moment is influenced by the electronegativity and size of the atoms.
- Fluorine is more electronegative than chlorine, but its small size leads to a smaller dipole moment in fluoromethane compared to chloromethane.
- Therefore, the dipole moment of fluoromethane is **less** than that of chloromethane, making this statement **incorrect**.

### Step 4: Analyze Statement IV
**Statement IV:** `NH2NH2.HCl` shows a positive test for nitrogen in Lassaigne's test.

- **Analysis:**
- Lassaigne's test detects nitrogen in organic compounds.
- Since `NH2NH2.HCl` contains nitrogen, it will give a positive test for nitrogen.
- Thus, this statement is **correct**.

### Step 5: Analyze Statement V
**Statement V:** Dipole moment of difluoromethane is more than dichloromethane.

- **Analysis:**
- The dipole moment of difluoromethane (DFM) is indeed greater than that of dichloromethane (DCM) due to the higher electronegativity of fluorine compared to chlorine.
- The experimental values support this, with DFM having a dipole moment of approximately 1.97 D and DCM around 1.60 D.
- Thus, this statement is **correct**.

### Conclusion
The incorrect statements are:
- Statement I: `CHCl3` is less acidic than `CHF3` (Incorrect)
- Statement II: Dipole moment of chlorobenzene is more than chlorocyclohexane (Incorrect)
- Statement III: Dipole moment of fluoromethane is more than chloromethane (Incorrect)

### Final Answer
The incorrect statements are I, II, and III.

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