Methyl alcohol $(CH_3OH)$,ethyl alcohol $(C_2H_5OH)$,and acetone $(CH_3COCH_3)$ were treated with iodine and sodium hydroxide solutions. Which substances will give the iodoform test?

Which of the following arrangements with respect to their reactivity in nucleophilic addition reaction is correct?

$A$ carbonyl compound $P$,which gives a positive iodoform test,undergoes reaction with $MeMgBr$ followed by dehydration to give an olefin $Q$. Ozonolysis of $Q$ leads to a dicarbonyl compound $R$,which undergoes intramolecular aldol reaction to give predominantly $S$.
$P$ $\xrightarrow[\substack{2. H^{+}, H_2 O \\ 3. H_2 SO_4, \Delta}]{1. MeMgBr} Q$ $\xrightarrow[2. Zn, H_2 O]{1. O_3} R$ $\xrightarrow[2. \Delta]{1. OH^{-}} S$
$1.$ The structure of the carbonyl compound $P$ is
$2.$ The structures of the products $Q$ and $R$,respectively,are
$3.$ The structure of the product $S$ is
Give the answer for questions $1, 2$ and $3.$

$CH_3CHO \xrightarrow{LiAlH_4} CH_3CH_2OH$
Which nucleophile is added in this reaction?

Which of the following compounds is reduced to the corresponding hydrocarbon by $Zn-Hg$ and concentrated $HCl$?

Give the conversion of the following:
$(i)$ $\text{Pent-3-en-2-one}$ from $\text{Ethanal}$
$(ii)$ $\text{Pent-2-enal}$ from $\text{Ethanal}$