The correct order regarding electronegativity of hybrid orbitals of carbon is

What is the hybridization of $C$ atoms in graphite?

Number of unhybridised orbitals in vinyl acetylene is

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

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.

Give examples of hybridization involving $s$,$p$,and $d$ orbitals.