The elements $N$,$P$,$As$,$Sb$,and $Bi$ belong to which group?

Which of the following statements is incorrect?

The number of bridged oxygen atoms present in compound $B$ formed from the following reactions is
$Pb(NO_3)_2 \xrightarrow{673 \ K} A + PbO + O_2$
$A \xrightarrow{\text{Dimerise}} B$

The compound$(s)$ which generate$(s)$ $N_2$ gas upon thermal decomposition below $300^{\circ} C$ is (are)
$A. NH_4NO_3$
$B. (NH_4)_2Cr_2O_7$
$C. Ba(N_3)_2$
$D. Mg_3N_2$

On heating,lead$(II)$ nitrate gives a brown gas $(A).$ The gas $(A)$ on cooling changes to a colourless solid/liquid $(B).$ $(B)$ on heating with $NO$ changes to a blue solid $(C).$ The oxidation number of nitrogen in solid $(C)$ is :

Dilute sodium hydroxide does not react with which of the following?