Which compound gives lactic acid on hydrolysis after reacting with $HCN$?

Which of the following reactants on reaction with conc. $NaOH$ followed by acidification gives the following lactone as the only product?

Which of the following compounds would undergo aldol condensation,which the Cannizzaro reaction and which neither? Write the structures of the expected products of aldol condensation and Cannizzaro reaction.
$(i)$ Methanal $(ii)$ $2-$Methylpentanal $(iii)$ Benzaldehyde $(iv)$ Benzophenone $(v)$ Cyclohexanone $(vi)$ $1-$Phenylpropanone $(vii)$ Phenylacetaldehyde $(viii)$ Butan$-1-$ol $(ix)$ $2,2-$Dimethylbutanal

The iodoform test can differentiate between:
$A$. Methanol and Ethanol
$B$. $CH_3COOH$ and $CH_3CH_2COOH$
$C$. Cyclohexene and cyclohexanone
$D$. Diethyl ether and Pentan$-3-$one
$E$. Anisole and acetone
Choose the correct answer from the options given below:

The final product $A$ in the following reaction sequence is:

In the following reaction:
$\text{Aldehyde} + \text{Alcohol} \xrightarrow{HCl} \text{Acetal}$
$HCHO \qquad ^tBuOH$
$CH_3CHO \qquad MeOH$
The best combination for the formation of acetal is: