Which of the following statements are correct ?

Options

A. Inductive effect causes permanent polarity in the molecule
B. Free radicals have odd electron in a p-orbital
C. All C-C bond length are same in Buta-1,3-diene
D. Hyperconjugation also affects the dipole moment of the molecule

Explanation

To determine which statements are correct, let's analyze each statement step by step.

### Step 1: Analyze Statement A
**Statement A:** Inductive effect causes permanent polarity in the bond.

- **Explanation:** The inductive effect refers to the permanent polarization of a bond due to the electronegativity difference between atoms. For example, in alcohols, the -OH group exerts a -I (negative inductive) effect, leading to a partial negative charge on oxygen and a partial positive charge on the carbon atom. This creates a permanent dipole in the molecule.

**Conclusion:** This statement is **correct**.

### Step 2: Analyze Statement B
**Statement B:** Free radicals have odd electrons in p-orbitals.

- **Explanation:** Free radicals are species that contain an unpaired electron. This unpaired electron can reside in a p-orbital. For instance, in the methyl radical (CH3•), the unpaired electron is in the p-orbital, which confirms that free radicals indeed have odd electrons in their p-orbitals.

**Conclusion:** This statement is **correct**.

### Step 3: Analyze Statement C
**Statement C:** All C-C bond lengths are the same in buta-1,3-diene.

- **Explanation:** Buta-1,3-diene has alternating single and double bonds: CH2=CH-CH=CH2. The bond lengths of C=C (double bond) and C-C (single bond) are different. The C=C bond length is approximately 145.4 picometers, while the C-C bond length is about 133.8 picometers. Therefore, not all C-C bond lengths are the same in buta-1,3-diene.

**Conclusion:** This statement is **incorrect**.

### Step 4: Analyze Statement D
**Statement D:** Hyperconjugation also affects the dipole moment of the molecule.

- **Explanation:** Hyperconjugation involves the interaction of σ-bonds with an adjacent empty or partially filled p-orbital. This interaction can influence the distribution of electron density in a molecule, thereby affecting its dipole moment. The presence of hyperconjugation can lead to changes in polarity and thus affect the dipole moment.

**Conclusion:** This statement is **correct**.

### Final Answer
The correct statements are A, B, and D.

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