Consider a positively charged $C_2H_3$ species in which the positively charged carbon is $sp$-hybridized,the uncharged carbon is $sp^2$-hybridized and an empty $p$-orbital is perpendicular to the $\pi$ system. What is the best description of this cation?

The compounds containing $sp$-hybridised carbon atom are:
$(I)$ $H_3C-N(CH_3)-CHO$
$(II)$ Pyridine
$(III)$ $H_3C-CN$
$(IV)$ $H_2C=C=CH-CH_3$

Among the following compounds,which have more than one type of hybridization for carbon atoms?
$(i) CH_3CH_2CH_2CH_3$
$(ii) CH_3-CH=CH-CH_3$
$(iii) CH_2=CH-C\equiv CH$
$(iv) HC\equiv CH$

$(a)$ Discuss the concept of hybridization. What are its different types in a carbon atom.
$(b)$ What is the type of hybridization of carbon atoms marked with a star in the following structures:
$(a)$ $\overset{*}{C}H_2 = CH - C(=O)OH$
$(b)$ $CH_3 - \overset{*}{C}H_2 - OH$
$(c)$ $CH_3 - CH_2 - \overset{*}{C}H = O$
$(d)$ $\overset{*}{C}H_3 - CH = CH - CH_3$
$(e)$ $CH_3 - \overset{*}{C} \equiv CH$

In the molecule $HC^{1} \equiv C^{2} - CH^{3} = CH^{4} - CH_{3}^{5}$,which carbon atom exhibits the lowest electronegativity?

The number of $sp$ and $sp^2$ hybridized carbon atoms in Hepta$-1, 3-$dien$-5-$yne,respectively,are