The markownikoff’s rule is used in connection with -

Options

A. Stereochemistry of elimination reactions
B. Stability of free radicals.
C. Activity of enzymes
D. Addition of acids to double bonds

Answer

**Step-by-Step Solution:**

1. **Understanding Markovnikov's Rule**: Markovnikov's rule is a principle in organic chemistry that predicts the outcome of the addition reactions of protic acids (like HCl, HBr, HI) to alkenes. It states that when a protic acid adds to an asymmetric alkene, the hydrogen atom (H+) will attach to the carbon atom that has more hydrogen atoms already attached (the more substituted carbon), while the halide (X-) will attach to the carbon with fewer hydrogen atoms.

2. **Identifying the Context**: The question asks what Markovnikov's rule is used in connection with. The options provided are:
- Stereochemistry
- Stability
- Activity
- Addition

3. **Analyzing the Options**:
- **Stereochemistry**: This refers to the spatial arrangement of atoms in molecules. While related, it is not the primary focus of Markovnikov's rule.
- **Stability**: This term refers to the stability of intermediates or products but does not directly relate to the rule itself.
- **Activity**: This term is vague in this context and does not specifically relate to the addition reactions described by Markovnikov's rule.
- **Addition**: This option directly relates to the addition reactions of alkenes with protic acids, which is the essence of Markovnikov's rule.

4. **Conclusion**: Based on the analysis, Markovnikov's rule is primarily used in connection with addition reactions of alkenes with protic acids.

**Final Answer**: Markovnikov's rule is used in connection with **addition** reactions.

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