In the given reaction,the reactant is $\gamma$-valerolactone. Predict the product $[X]$ for the reaction: $\text{Reactant} \xrightarrow{H_2O/H^{+}} [X]$.

The correct order of acidic strength is

What is the product of the following reaction?

How many of the following compounds react with $NaHCO_3$ to evolve $CO_2$ gas?
$I$: $3$-Nitrophenol
$II$: $2,4$-Dinitrophenol
$III$: $4$-Hydroxybenzoic acid
$IV$: $4$-Methylbenzoic acid
$V$: $4$-Chlorophenol
$VI$: $2,4$-Dinitrotoluene
$VII$: $4$-Hydroxybenzenesulfonic acid
$VIII$: $4$-Sulfobenzoic acid
$IX$: Squaric acid
$X$: Maleic acid

Which of the following acids has the highest $pK_{a}$ value?

The relative reactivities of acyl compounds towards nucleophilic substitution are in the order of