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

(N/A) The shapes of the molecules based on hybridization are as follows:
$1$. $BCl_3$: The central boron atom undergoes $sp^2$ hybridization. It forms three $\sigma$-bonds with chlorine atoms,resulting in a trigonal planar geometry.
$2$. $CH_4$: The central carbon atom undergoes $sp^3$ hybridization. It forms four $\sigma$-bonds with hydrogen atoms,resulting in a tetrahedral geometry.
$3$. $CO_2$: The central carbon atom undergoes $sp$ hybridization. It forms two $\sigma$-bonds with oxygen atoms,resulting in a linear geometry $(: \ddot{O} = C = \ddot{O} :)$.
$4$. $NH_3$: The central nitrogen atom undergoes $sp^3$ hybridization. It has three $\sigma$-bonds and one lone pair,resulting in a pyramidal shape.