Identify A and B ibn the following reaction : `CH_(3)+Br+Mg overset("dry either")to A+CO_(2)overset("dry either")underset(H^(+)//H_(2)O) to B+Mg(B r)OH`

Explanation

To solve the given reaction and identify compounds A and B, we can break down the process step by step.

### Step 1: Identify the Initial Reactants
The initial reactants provided in the reaction are:
- CH₃ (which represents the methyl group, or methane, CH₄)
- Br (bromine)
- Mg (magnesium)
- Dry ether (as a solvent)
...