Which one of the following is not formed by aldol condensation of a mixture of ethanal and propanal?

The main reduction product of the following compound with $NaBH_4$ in methanol is

$C_7H_6O$ is the molecular formula of $X$,which gives a negative Fehling test but a positive Tollen's test. $X$ $\xrightarrow[AcONa]{Ac_2O} Y$ $\xrightarrow[Me_2NH]{1. SOCl_2} Z$. The correct option is:

The major product formed in the following reaction is:

Which of the following compounds ($i$ through $v$) should not be classified as an acetal?

Given below are two statements :
Statement $I :$ The nucleophilic addition of sodium hydrogen sulphite to an aldehyde or a ketone involves proton transfer to form a stable ion.
Statement $II :$ The nucleophilic addition of hydrogen cyanide to an aldehyde or a ketone yields amine as final product.
In the light of the above statements,choose the most appropriate answer from the options given below :