Product $A$ in the reaction will be:

Which of the following represents the Gatterman-Koch reaction?

For the reaction sequence: $P$ $\xrightarrow[2. H_3O^+]{1. CH_3MgBr} R$ $\xrightarrow[2. \Delta]{1. \text{dil. } NaOH} \text{4-methylpent-3-en-2-one}$,identify $P$.

Identify the 'product' in the following reaction: $\text{Pent-3-enenitrile} \xrightarrow{DIBAL-H, H_3O^+} \text{Product}$

Acetophenone is prepared from

$Ph - C \equiv C - CH_3 \xrightarrow{Hg^{2+}/H^+} A$. What is $A$?