[A]⟶ reduction [B]⟶CHCl3+KOH[C]⟶ reduction N− Methylaniline, A is?FormaldehydeTrichloromethaneNitrobenzeneToluene

To identify compound A based on the given reactions, we will analyze the transformations step by step.

1. Reduction of A to B: The reaction starts with compound A, which undergoes a reduction to yield compound B. In an organic context, this often suggests that compound A could be a compound that, upon reduction, loses oxygen or forms a new carbon-hydrogen bond.

2. Formation of B: From the information, compound B is involved in a reaction to produce CHCl₃ (trichloromethane) in the presence of KOH. This suggests that B could be a chlorinated or a functionalized compound that can further react to yield CHCl₃.

3. Final Step: The reduction of B to C indicates that B can then be reduced to yield the final product, which is N-Methylaniline, C. This implies a transformation where an aromatic ring becomes substituted.

Now, let’s examine the possible candidates for A:

• Formaldehyde: This is a simple aldehyde that doesn't fit the reduction to B type.
• Trichloromethane: This is the same as the product produced alongside KOH and can't be the starting material.
• Nitrobenzene: This can be reduced to an amine, but initially yields a different path not leading to CHCl₃.
• Toluene: It can undergo oxidation to form benzaldehyde, which can further be chlorinated in the presence of strong bases.

Given this reasoning, A is most likely Toluene because it can be oxidized to benzaldehyde and subsequently to give rise to the products mentioned through further reactions, including being involved in the formation of CHCl₃.

Final Answer

A is Toluene.