`C_(7)H_(10)O` reacts with `CH_(3)MgBr` r to give a compound `C_(8)H_(10)O` which gives the test with iodoform, than fine out structure of A

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Answer

To solve the problem, we need to identify the structure of compound A (C7H10O) that reacts with CH3MgBr to yield a compound C8H10O, which gives a positive iodoform test.

### Step-by-step Solution:

1. **Identify the Reactants and Products:**
- The starting compound has the formula C7H10O.
- It reacts with CH3MgBr (methyl magnesium bromide), which is a Grignard reagent.
- The product has the formula C8H10O and gives a positive iodoform test.

2. **Understanding the Iodoform Test:**
- The iodoform test is positive for compounds that have a methyl ketone (RCOCH3) or a secondary alcohol that can be oxidized to a methyl ketone.
- Therefore, the product C8H10O must contain a structure that can yield a methyl ketone.

3. **Reaction with Grignard Reagent:**
- Grignard reagents react with carbonyl compounds (like aldehydes and ketones) to form alcohols.
- The reaction can be represented as:
\[ \text{C7H10O} + \text{CH3MgBr} \rightarrow \text{C8H10O (after hydrolysis)} \]
- The product will have an additional carbon from the Grignard reagent.

4. **Possible Structures for C7H10O:**
- We need to consider possible structures for C7H10O that can lead to a product with a methyl ketone after the reaction.
- A likely candidate for C7H10O is an unsaturated aldehyde or ketone.

5. **Testing the Structure:**
- Let's assume C7H10O is 3-hexanone (an example structure).
- The reaction with CH3MgBr would yield:
\[ \text{3-hexanone} + \text{CH3MgBr} \rightarrow \text{4-heptanol (after hydrolysis)} \]
- The resulting compound (4-heptanol) can be oxidized to 3-heptanone, which is a methyl ketone and will give a positive iodoform test.

6. **Conclusion:**
- After analyzing the structures and reactions, we conclude that the structure of compound A (C7H10O) is likely to be 3-hexanone, which upon reaction with CH3MgBr gives a product that can yield a methyl ketone, thus passing the iodoform test.

### Final Answer:
The structure of compound A (C7H10O) is 3-hexanone.