Which one of the following gives a yellow precipitate with iodine and $NaOH$ solution?

$3 CH_3COCH_3 \xrightarrow{HCl} (CH_3)_2C = CH - CO - CH = C(CH_3)_2$
This product $B$ is obtained when acetone is saturated with hydrogen chloride gas. $B$ can be:

Considering the following reaction sequence,the correct statement$(s)$ is(are):
$A$. Compounds $P$ and $Q$ are carboxylic acids.
$B$. Compound $S$ decolorizes bromine water.
$C$. Compounds $P$ and $S$ react with hydroxylamine to give the corresponding oximes.
$D$. Compound $R$ reacts with dialkylcadmium to give the corresponding tertiary alcohol.

Benzene carbaldehyde (benzaldehyde) is reacted with concentrated $NaOH$ solution to give the products $A$ and $B$. The product $A$ can be used as a food preservative and the product $B$ is an aromatic hydroxy compound where the $OH$ group is linked to an $sp^3$ hybridized carbon atom next to the benzene ring. The products $A$ and $B$ are respectively,

Which of the following statements is true regarding the Cannizzaro reaction?

Acetaldehyde forms a white crystalline precipitate on mixing with a ...... solution of