During the conversion of $PCl_3$ to $PCl_5$,the hybridisation of the $P$ atom changes from .......

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

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

The mean values for the radial distance for different phosphorus orbitals are $3s: 0.47 \ \mathring{A}$,$3p: 0.55 \ \mathring{A}$,$3d: 2.4 \ \mathring{A}$. When $P$ is going to form $PF_5$,then these radial distances are going to become arbitrarily . . . . . . , . . . . . . and . . . . . . respectively.

Describe the shapes of $BF_3$ and $BH_4^-$. Assign the hybridisation of boron in these species.

Which of the following is a linear molecule?