As the $s$-character of the hybrid orbital decreases,the bond angle ...........

What is the hybridization of the nitrogen atomic orbitals in $NO_2^+$,$NO_3^-$,and $NH_4^+$ respectively?

The structure of $CH_2Cl_2$ (dichloromethane) is:

Among the triatomic molecules/ions,$BeCl_2, N_3^{-}, N_2O, NO_2^{+}, O_3, SCl_2, ICl_2^{-}, I_3^{-}$ and $XeF_2$,the total number of linear molecule$(s)$/ion$(s)$ where the hybridization of the central atom does not have contribution from the $d$-orbital$(s)$ is
[Atomic number: $S=16, Cl=17, I=53$ and $Xe=54$ ]

$A + 2Cl^{-} \rightarrow B$
Where $A$ is $PCl_4^+$ and $B$ is $PCl_6^-$.
Which of the following statements is $INCORRECT$:
$(I)$ From $B$ to $A$,the number of $d$-orbitals involved in hybridization increases.
$(II)$ From $A$ to $B$,the percentage of $p$-character in the $P-Cl$ bond increases.
$(III)$ The number of covalent bonds in $A$ and $B$ are the same.
$(IV)$ $B$ is a product of Lewis acid-base interaction,which is associated with super-octet molecules only.

Which $C$ atom is the most electronegative in the structure $CH_3^{III} - CH_2^{II} - C \equiv CH^I$?