Which of the following statement (s) is/are correct ?

Options

A. Inductive effect is permanent shifting of `sigma overline e^, s` towards more `EN` element.
B. Mesomeric effect is delocalisation of `L P bar(e),s` with `pi bar(e),s` in conjugation.
C. Hyperconjugation is simultaneous shift of `sigma` and `pi overline e^, s` at `1,3-position` without the movement of `H` atom from its position.
D. Tautomerism is simultaneous shift of `sigma` and `pi overline e^, s` at `1,3-position` with the movemet of `H` atom from its position.

Explanation

To determine which of the statements regarding inductive effect, mesomeric effect, hyperconjugation, and tautomerism are correct, let's analyze each statement step by step.

### Step 1: Analyze Statement A
**Statement A:** Inductive effect is the permanent shifting of sigma electrons towards the more electronegative element.

**Explanation:** The inductive effect occurs when a more electronegative atom (let's say X) pulls the sigma electrons towards itself, creating a partial negative charge on X and a partial positive charge on the adjacent atom (like carbon). This effect is permanent and can influence the entire molecule, typically extending up to 3-4 carbon atoms away from the electronegative atom.

**Conclusion:** Statement A is correct.

### Step 2: Analyze Statement B
**Statement B:** Mesomeric effect is the delocalization of lone pair electrons with the pi electrons in conjugation.

**Explanation:** The mesomeric effect involves the delocalization of electrons, particularly the lone pair of electrons on an atom (like nitrogen) that can interact with adjacent pi bonds. For example, in the compound CH2=CH-NH2, the lone pair on nitrogen can participate in resonance with the double bond, leading to a distribution of electron density across the molecule.

**Conclusion:** Statement B is correct.

### Step 3: Analyze Statement C
**Statement C:** Hyperconjugation is the simultaneous shift of the sigma and pi electrons at the 1,3 position without the movement of hydrogen atom from its position.

**Explanation:** Hyperconjugation refers to the interaction between the electrons in a sigma bond (usually C-H or C-C) and an adjacent empty or partially filled p-orbital or pi bond. This effect stabilizes the molecule without any movement of hydrogen atoms from their positions. It typically involves the presence of alpha hydrogens adjacent to a double bond or a positively charged carbon.

**Conclusion:** Statement C is correct.

### Step 4: Analyze Statement D
**Statement D:** Tautomerism is the simultaneous shifting of sigma and pi electrons at the 1 and 3 position with the movement of the H atom from its position.

**Explanation:** Tautomerism is a type of isomerism where the structure can interconvert between two forms, typically involving the movement of a hydrogen atom and a shift in the position of double bonds. For example, in keto-enol tautomerism, the hydrogen atom shifts from the carbon to the oxygen, resulting in a change in the bonding structure.

**Conclusion:** Statement D is correct.

### Final Conclusion
All statements A, B, C, and D are correct.

### Summary of Correct Statements:
- A: Correct
- B: Correct
- C: Correct
- D: Correct