Three molecules of acetone in the presence of dry $HCl$ form:

The major product of the following reaction is:

Which of the following is reacted with benzaldehyde to obtain $1-$phenylethanol?

The reaction of $A$ to give $B$ and $C$ as shown in the reaction scheme is an example of:
$CH_2=CH_2$ $\xrightarrow[2. Zn/H_2O]{1. O_3} A$ $\xrightarrow{Conc. NaOH} B + C$
(Where $B$ is an alcohol and $C$ is a sodium salt of a carboxylic acid)

Predict the products of the following reactions with $CH_3CHO$:
$(i) CH_3CHO + C_6H_5MgBr$
$(ii) CH_3CHO + C_6H_{11}MgBr$
$(iii) CH_3CHO + (CH_3)_2CHMgBr$
Followed by acidic hydrolysis in each case.

$A$ and $B$ in the following reaction are: