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

The $C-H$ bond and $C-C$ bond in ethane are formed by which of the following types of overlap?

Is there any change in the hybridisation of $B$ and $N$ atoms as a result of the following reaction?
$BF_{3} + NH_{3} \rightarrow F_{3}B \cdot NH_{3}$

Which molecule has $sp^3$ hybridization of the central atom?

Which type of overlap is involved in the formation of $O-H$ bonds in a water molecule?

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