Which of the following halides does not form `G.R` when treated with magnesium in the presence of ether ?

Options

A.
B.
C.
D.

Explanation

To determine which halide does not form a Grignard reagent when treated with magnesium in the presence of ether, we need to analyze the nature of the halides provided. Grignard reagents are formed when alkyl or aryl halides react with magnesium, but certain functional groups can interfere with this reaction.

### Step-by-Step Solution:

1. **Understanding Grignard Reagents**: Grignard reagents are organomagnesium compounds formed by the reaction of magnesium with alkyl or aryl halides in an anhydrous ether solvent. They are highly reactive and can react with water and other protic solvents.

2. **Identifying Active Hydrogen**: Active hydrogen refers to hydrogen atoms that are acidic and can react with magnesium. Compounds containing -OH (alcohols), -COOH (carboxylic acids), or -NH (amines) groups typically have active hydrogens.

3. **Analyzing the Halides**:
- **Option A**: If the halide contains a -COOH (carboxylic acid) group, the acidic hydrogen will react with magnesium, preventing the formation of the Grignard reagent.
- **Option B**: If the halide has a -OH (alcohol) group, the active hydrogen will also react with magnesium, inhibiting the formation of the Grignard reagent.
- **Option C**: If the halide has a -NO2 (nitro) group, while it is an electron-withdrawing group, it does not contain active hydrogen that would interfere with the Grignard formation.
- **Option D**: Similar to option A, if the halide has a -COOH group, it will also not form a Grignard reagent due to the presence of active hydrogen.

4. **Conclusion**: Based on the analysis, options A, B, and D contain active hydrogens that prevent the formation of Grignard reagents. Therefore, the halides that do not form Grignard reagents are those with -COOH and -OH groups.

### Final Answer:
The halides that do not form Grignard reagents when treated with magnesium in the presence of ether are those containing active hydrogens, specifically options A, B, and D.