$A$ solution of $1$-chloro-$1$-phenylethane in toluene undergoes direct racemization in the presence of a small amount of $SbCl_5$ due to the formation of:

Which of the following is the most reactive towards $S_{N}1$ mechanism?

The products $A$ and $B$ in the following reactions,respectively,are:
$A \xleftarrow{AgNO_2} CH_3-CH_2-CH_2-Br \xrightarrow{AgCN} B$

Identify the structure of the major product in the following reaction:
$Ph-CH(Br)-CH(Br)-CHO \xrightarrow[\Delta]{K_2CO_3} ?$

$A$ dihalogen derivative $X$ of a three-carbon hydrocarbon reacts with alcoholic $KOH$ to give another hydrocarbon,which gives a red precipitate with ammoniacal $Cu_2Cl_2$. Reaction of $X$ with aqueous $KOH$ gives an aldehyde. The compound $X$ is .......

$A$ bottle containing $C_6H_5I$ and $C_6H_5CH_2I$ has lost its label. To identify them,samples $A$ and $B$ are taken in separate test tubes and boiled with $NaOH$ solution. Finally,the solution in each test tube is acidified with dilute $HNO_3$ and then a few drops of $AgNO_3$ solution are added. Substance $B$ gives a yellow precipitate. Which statement is correct for this process?