What is the product formed when acetone reacts with $I_2$ in the presence of $NaOH$?

Identify the major product of the following reaction:

What will be the product $S$ in the following reaction?
$CH_3COOH$ $\xrightarrow{SOCl_2} P$ $\xrightarrow[Anhyd. AlCl_3]{Benzene} Q$ $\xrightarrow{HCN} R$ $\xrightarrow{HOH} S$

The major product formed in the following reaction is:

The best reagent to carry out the following conversion is:
$3$-hydroxyethylcyclopentane-$1$-carbaldehyde $\rightarrow$ $1$-ethyl-$3$-methylcyclopentane (with a hydroxy group on the ethyl side chain).
(Note: The image shows the reduction of an aldehyde group $-CHO$ to a methyl group $-CH_3$ while keeping the secondary alcohol $-CH(OH)CH_3$ intact.)

The above conversion can be carried out by: