For making a distinction between $2$-pentanone and $3$-pentanone,the reagent to be employed is

Statement $I$: Aldehyde on reaction with $HCN$ gives Cyanohydrin.
Statement $II$: Cyanohydrin is a compound which consists of hydroxy and cyano groups on the same carbon.
Choose the correct answer from the following with reference to above statements.

Which of the following reactions involve the carbon-carbon bond formation?

When $m$-chlorobenzaldehyde is treated with $50\%$ $KOH$ solution,the product$(s)$ obtained is (are):

Find the major product of the following reaction: $C_6H_5CHO + CH_3CHO \xrightarrow{Ca(OH)_2, \Delta} ?$

The end product $(C)$ in the following reaction is: