The number of primary, secondary and tertiary carbons in the following structure are respectively:

The number of $1°$ carbon of following compound is

${\mathrm{CH}}_3-\underset{\stackrel{|}{{\mathrm{CH}}_3}}{\overset{\underset{|}{{\mathrm{CH}}_3}}{\mathrm{C}}}-{\mathrm{CH}}_2-\underset{\stackrel{|}{{\mathrm{CH}}_3}}{\overset{\underset{|}{{\mathrm{CH}}_3}}{\mathrm{C}}}-{\mathrm{CH}}_3$

Which type of hybridisation of each carbon have in the following compounds?

(1) ${\mathrm{CH}}_3-\mathrm{Cl}$

(2) ${\mathrm{CH}}_3-\underset{\stackrel{\left|\right|}{\mathrm{O}}}{\mathrm{C}}-{\mathrm{CH}}_3$

(3) ${\mathrm{CH}}_3-\mathrm{C}\equiv \mathrm{N}$

(4) $\mathrm{H}-\underset{\stackrel{\left|\right|}{\mathrm{O}}}{\mathrm{C}}-{\mathrm{NH}}_2$

Number of $\mathrm{\pi }$ electrons in  are: