The product of the following reaction is :

Identify the major product of the following reaction:

Write down functional isomers of a carbonyl compound with molecular formula $C_3H_6O$. Which isomer will react faster with $HCN$ and why? Explain the mechanism of the reaction also. Will the reaction lead to the completion with the conversion of whole reactant into product at reaction conditions? If a strong acid is added to the reaction mixture what will be the effect on concentration of the product and why?

Identify the product $A$ in the following reaction:
$\text{Substrate} \xrightarrow{MnO_2} A$
(The substrate is a benzene ring with a $-OH$ group,a $-COOH$ group,and a $-CH(CH_2CH_3)CHO$ group attached to it.)

The product $B$ is formed by the reaction of cyclohexanone with hydroxylamine $(NH_2OH)$ to form an oxime $(A)$,followed by a Beckmann rearrangement using polyphosphoric acid $(PPA)$. Identify the product $B$.

Reactant $(A)$ is: