Which of the following compounds exhibits $sp^2$ hybridization?

The hybridization of the central atom will change when

Which of the following molecules is linear?

Predict the shapes of the following molecules on the basis of hybridization:
$BCl_3, CH_4, CO_2, NH_3$

How many $sp^2$ and $sp$ hybridized carbon atoms are present respectively in the following compound? (The structure is $1,2-didehydrobenzene$ or $benzyne$ derivative,specifically $1,2-didehydrocyclohexadiene$ structure shown in the image).

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 $Y$.