Hyperconjugation involves delocalization of

Options

A. electrons of carbon-hydrogen `sigma` bond of an alkyl group directly attached to an atom of unsaturated system
B. electrons of carbon-hydrogen `sigma` bond of alkyl group directly attached to the positively charged carbon atom
C. `pi`- electons of carbon -carbon bond
D. lone pair of electrons

Explanation

**Step-by-Step Solution:**

1. **Understanding Hyperconjugation:**
Hyperconjugation is a concept in organic chemistry that involves the delocalization of electrons. It is often referred to as "sigma resonance." This phenomenon occurs when the electrons in a sigma bond (specifically, C-H or C-C bonds) interact with an adjacent empty or partially filled p-orbital, leading to stabilization of the molecule.

2. **Identifying the Structure:**
Consider a carbocation (a positively charged carbon atom) that is adjacent to an alkyl group. For example, if we have a carbocation (C+) next to a carbon atom that is part of a CH3 (methyl) group, this adjacent carbon is known as the alpha carbon.

3. **Mechanism of Hyperconjugation:**
In hyperconjugation, the sigma bond between the alpha carbon and the hydrogen (or another carbon) can interact with the empty p-orbital of the carbocation. The electrons from the sigma bond can shift towards the carbocation, effectively stabilizing it. This can be visualized as the sigma bond breaking and forming a pi bond, which helps to distribute the positive charge.

4. **Evaluating the Options:**
Now, let’s analyze the provided options:
- **Option A:** Electrons of carbon-hydrogen sigma bond of an alkyl group directly attached to an atom of an unsaturated system. This is incorrect because hyperconjugation stabilizes carbocations, not unsaturated systems.
- **Option B:** Electrons of carbon-hydrogen sigma bond which is correct of an alkyl group directly attached to the positively charged carbon atom. This is correct as it describes the interaction that stabilizes the carbocation.
- **Option C:** Pi pi electrons of carbon bond. This is incorrect because hyperconjugation involves sigma bonds, not pi bonds.
- **Option D:** Lone pair of electrons. This is incorrect as hyperconjugation does not involve lone pairs but rather sigma bonds.

5. **Conclusion:**
Based on the analysis, the correct answer is **Option B**: "Electrons of carbon-hydrogen sigma bond which is correct of an alkyl group directly attached to the positively charged carbon atom."

---