Paraldehyde is a trimer of which of the following?

In Tollen's test for aldehyde,the overall number of electron$(s)$ transferred to the Tollen's reagent formula $[Ag(NH_{3})_{2}]^{+}$ per aldehyde group to form silver mirror is $......$. (Round off to the Nearest integer)

The major product of the following reaction is:

$x$ is the product obtained from propanenitrile and stannous chloride in the presence of hydrochloric acid followed by hydrolysis. $y$ is the product obtained from but$-2-$ene by ozonolysis followed by hydrolysis. From the following, which product is not obtained when one mole of $x$ and one mole of $y$ react with each other in the presence of alkali followed by heating?

Which of the following can be used to convert $3$-methylbutan-$2$-one into isopentane?

The major product of the following reaction is