The major product of the following reaction is:

Which of the following compounds is the slowest to react with nitrosonium ion $(NO^{+})$?

What is the product $R$ in the following reaction sequence?

Match the compounds in Column-$I$ with their respective intermolecular attraction forces in Column-$II$.

Column-$I$ (Compound)	Column-$II$ (Attraction Forces)
$A$. Aldehyde	$i$. Intermolecular hydrogen bond formed in $ROH$ between $O^{\delta -}$ of one molecule and $H^{\delta +}$ of another molecule.
$B$. Ketone	$ii$. Dipole-dipole forces between $C^{\delta +}$ of one molecule and $O^{\delta -}$ of another molecule.
$C$. Alcohol	$iii$. van der Waals forces
$D$. Alkane	$iv$. Ionic forces

Fehling solution reacts with $HCHO$ to form a precipitate of which color?

Compound $A$ $(C_9H_{10}O)$ shows a positive iodoform test. Oxidation of $A$ with $KMnO_4/KOH$ gives acid $B$ $(C_8H_6O_4)$. The anhydride of $B$ is used for the preparation of phenolphthalein. Compound $A$ is: