Which of the following has a linear structure?

Suggest reasons why the $B-F$ bond lengths in $BF_3\ (130\ pm)$ and $BF_4^-\ (143\ pm)$ differ.

The hybridisation of xenon atom in $XeF_4$ is

The hybridizations of $C_2$ and $C_3$ in the molecule $H_3C-CH=C=CH-CH_3$ are respectively:

Write the bond angle and hybridization type of the water molecule.

Choose the correct code of characteristics for the given order of hybrid orbitals of the same atom,$sp < sp^2 < sp^3$:
$(i)$ Electronegativity
$(ii)$ Bond angle between same hybrid orbitals
$(iii)$ Size
$(iv)$ Energy level