The hybridisation of $N$ in $NO_2^{+}$,$NO_3^{-}$ and $NH_4^{+}$ respectively is

Two $p$-block elements $X$ and $Y$ form fluorides of the type $EF_3$. The fluoride compound $XF_3$ is a Lewis acid and $YF_3$ is a Lewis base. The hybridization of the central atoms of $XF_3$ and $YF_3$ respectively are

What is the hybridisation of carbon $C_2$ and $C_4$ respectively in the molecule $CH_3-CH=CH-CH_3$?

In which of the following pairs of molecules/ions,the central atoms have $sp^{2}$ hybridisation?

Consider the following statements for $\dot{CH_3} = X$ and $\dot{CF_3} = Y$:
$I$. When $X$ dimerises,the bond angle decreases.
$II$. When $X$ dimerises,the bond angle increases.
$III$. In the $X-Y$ molecule,the $C-C$ bond length is less than that in the $Y-Y$ molecule.
$IV$. The bond angle in $X$ is greater than that in $Y$.

The bond angle and $\%$ $d-$character in $S$ atom in $SF_6$ are