Which of the following has the highest $pK_b$ value?

Which of the following compounds is the strongest base?

Decarboxylation of all six possible isomers of diaminobenzoic acids $C_6H_3(NH_2)_2COOH$ yields three products $A, B$ and $C$. Three acids give product $A$,two acids give product $B$ and one acid gives product $C$. The melting point of product $C$ is .....$^{\circ} C$.

In the reaction sequence: $C_6H_5NH_2$ $\xrightarrow{CHCl_3/KOH, \Delta} (X)$ $\xrightarrow{LiAlH_4/H_2O} (Y)$,the product $(Y)$ is:

Which among the following is the strongest Bronsted base?

Ethyl amine on heating with $CS_2$ in presence of $HgCl_2$ forms