What is the hybridization of the central $I$ atom in the $I_3^-$ ion?

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 $Y$.

$X$ and $Y$ are two covalent molecules in which the hybridization of the central atoms is the same,but their shapes are different. $X$ and $Y$ are:

In which of the following molecules/ions is the central atom $sp^2$ hybridized?

Which of the following molecules has a shape similar to $CO_{2}$?

Identify the pair of molecules in which the hybridization of the central atom is $sp^2$ with bent geometry.