Which of the following bonds is the most acidic?

In the compound $HC \equiv C-CH=CH_2$,the hybridization of $C-2$ and $C-3$ carbons are respectively:

Determine the hybridization of the carbon atoms in the following compounds:
$(a)$ $N \equiv C-CH=CH_2$
$(b)$ $HC \equiv C-CH=CH_2$ (Identify the carbon atoms of the single bond $C-C$)
$(c)$ $HC \equiv C-C \equiv CH$
$(d)$ $H_2C=C=C=CH_2$
$(e)$ Buta$-1,3-$diene (as shown in the figure)

The hybridisation of the negatively charged carbon atoms in $(1)$ and $(2)$ are:
$(1)$ $CH_3^-$
$(2)$ $H_2C^- - CHO - CH_3$

Explain how the electronegativity of carbon atoms is related to their state of hybridization in an organic compound.

In the compound $CH_2=CH-CH_2-C \equiv CH$,what is the hybridization type of the $C_2-C_3$ bond?