In the acetylene molecule,the $C-H$ sigma bond is formed by the overlap of which orbitals?

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

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

Which of the following shows a linear structure?

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 of the following statements is true regarding the $PCl_5$ molecule?
$(i)$ The two axial $P-Cl$ bonds in $PCl_5$ are longer than the three equatorial bonds.
$(ii)$ The axial bonds in $PCl_5$ are stronger than equatorial bonds.
$(iii)$ The axial bonds in $PCl_5$ are more stable than equatorial bonds.
$(iv)$ All five bonds in $PCl_5$ molecule are equivalent.