What is the product obtained when acetamide is hydrolyzed in boiling acid?

Which among the given acids has the lowest $pKa$ value?

$HCOOH$ shows all tests of aldehyde because

Which of the following shows the correct order of decreasing acidity?

$n$-Propanol on treatment with concentrated $HBr$ gives $P$. The product $P$ on reaction with $KCN$ gave the product $Q$. The product $Q$ on heating with aqueous acidic solution,furnished the product $R$. The product $R$ is

$CH_3 - CH = CH - CH_2 - CO_2H \xrightarrow[\Delta ]{}(X) \,(major)$; Product $(X)$ is