What is the shape of the molecule $CH_2 = CH - CH = CH_2$?

The molecule having $sp^3d^2$ hybridisation is

What is the decreasing order of carbon-carbon single bond length in the following compounds?
$(I) CH_2 = CH - C \equiv CH$
$(II) CH \equiv C - C \equiv CH$
$(III) CH_3 - CH = CH_2$
$(IV) CH_2 = CH - CH = CH_2$

The formation of molecular complex $BF_3-NH_3$ results in a change in hybridization of boron

What is the bond angle $\angle F-B-F$ in $BF_3$ (in $^{\circ}$)?

The structures of $BCl_3$ and $BCl_3 \cdot NH_3$,respectively are