Which of the following reagents is used in the Hoffmann elimination reaction of amines?

In the reaction shown,the structure of the product $T$ is:

In the given reaction,the product $E$ is:

Identify the correct statements:
$(A)$ Primary amines do not give diazonium salts when treated with $NaNO_2$ in acidic conditions.
$(B)$ Aliphatic and aromatic primary amines on heating with $CHCl_3$ and ethanolic $KOH$ form carbylamines.
$(C)$ Secondary and tertiary amines also give the carbylamine test.
$(D)$ Benzenesulfonyl chloride is known as Hinsberg's reagent.
$(E)$ Tertiary amines react with benzenesulfonyl chloride very easily.
Choose the correct answer from the options given below:

In the following reaction sequence,$C_2H_5NH_2$ $\xrightarrow{HNO_2} A$ $\xrightarrow{PCl_5} B$ $\xrightarrow{NH_3} C$,the compound '$C$' is

Arrange the following in order of their decreasing acidic strength:
$(I)$ $CH_3NH_3^+$
$(II)$ $C_6H_5NH_3^+$
$(III)$ $[H_2N-C(=NH)-NH_2]H^+$
$(IV)$ $O_2N-C_6H_4-NH_3^+$