In which of the followinng compounds the carbon marked with asterisk is expected to have greatest positive charge?

Options

A. `overset(***)(C)H_(3)-CH_(2)-Cl`
B. `overset(***)(C)H_(3)-CH_(2)-Mg^(+)Cl^(-)`
C. `overset(***)(C)H_(3)-CH_(2)-Br`
D. `overset(***)(C)H_(3)-CH_(2)-CH_(3)`

Explanation

To determine which compound has the carbon marked with an asterisk expected to have the greatest positive charge, we will analyze the inductive effects of the substituents attached to the carbon in each option.

### Step-by-Step Solution:

1. **Identify the Compounds**:
- We have four compounds with a carbon marked with an asterisk. Let's denote them as:
- Option 1: Ethyl chloride (CH3-CH2-Cl)
- Option 2: Grignard reagent (R-MgX)
- Option 3: Ethyl bromide (CH3-CH2-Br)
- Option 4: A saturated hydrocarbon (not specified in the transcript)

2. **Analyze the Inductive Effect**:
- The inductive effect is the permanent effect of electron-withdrawing or electron-donating groups through sigma bonds.
- Chlorine (Cl) and bromine (Br) are both electronegative atoms that exhibit a -I (inductive withdrawal) effect.

3. **Compare Chlorine and Bromine**:
- Chlorine is more electronegative than bromine, which means that it will exert a stronger -I effect. Therefore, in ethyl chloride (Option 1), the carbon attached to chlorine will have a greater positive charge compared to the carbon in ethyl bromide (Option 3) due to chlorine's stronger electron-withdrawing ability.

4. **Evaluate the Grignard Reagent (Option 2)**:
- In the Grignard reagent (R-MgX), the carbon (R) is bonded to magnesium, which is a metal. In this case, the carbon atom will carry a partial negative charge (δ-) because magnesium (Mg) carries a partial positive charge (δ+). Therefore, this option does not contribute to a positive charge on the carbon.

5. **Consider the Saturated Hydrocarbon (Option 4)**:
- The saturated hydrocarbon does not have any strong electron-withdrawing groups. The carbon in this compound is likely to have a very minimal positive charge, if any, due to the lack of electronegative substituents.

6. **Conclusion**:
- Based on the analysis, the carbon in ethyl chloride (Option 1) will have the greatest positive charge due to the strong -I effect of chlorine.

### Final Answer:
The compound in which the carbon marked with an asterisk is expected to have the greatest positive charge is **Option 1: Ethyl chloride (CH3-CH2-Cl)**.