When acetamide is treated with $HNO_2,$ the gas evolved is:

Order of basic strength: $(A) Ph-NH_2$,$(B) Ph-NH-CH_3$,$(C) Ph-N(CH_3)_2$,$(D) \text{o-toluidine (2-methylaniline)}$

Write the order of basic strength for the following compounds:

For the diazonium ions,the order of reactivity towards the diazo-coupling with phenol in the presence of dilute $NaOH$ is:
$(I)$ $Me_2N-C_6H_4-N_2^+$
$(II)$ $O_2N-C_6H_4-N_2^+$
$(III)$ $CH_3O-C_6H_4-N_2^+$
$(IV)$ $CH_3-C_6H_4-N_2^+$

The most acidic proton and the strongest nucleophilic nitrogen in the following compound are respectively:

Which of the following reactions does $NOT$ involve the replacement of the diazonium group?