Draw diagrams showing the formation of a double bond and a triple bond between carbon atoms in $C_{2}H_{4}$ and $C_{2}H_{2}$ molecules.

(N/A) $C_{2}H_{4}$:
The electronic configuration of $C$-atom in the excited state is $1s^{2} 2s^{1} 2p_x^{1} 2p_y^{1} 2p_z^{1}$.
In the formation of an ethene molecule $(C_{2}H_{4})$,one $sp^{2}$ hybrid orbital of carbon overlaps an $sp^{2}$ hybridized orbital of another carbon atom,forming a $C-C$ sigma bond. The remaining two $sp^{2}$ orbitals of each carbon atom form $sp^{2}-s$ sigma bonds with two hydrogen atoms. The unhybridized $2p_z$ orbital of each carbon atom undergoes sidewise overlap to form a weak $\pi$-bond.
$C_{2}H_{2}$:
In the formation of $C_{2}H_{2}$ molecule,each $C$-atom is $sp$ hybridized with two $2p$-orbitals in an unhybridized state.
One $sp$ orbital of each carbon atom overlaps along the internuclear axis forming a $C-C$ sigma bond. The second $sp$ orbital of each $C$-atom overlaps with a $1s$-orbital of a hydrogen atom to form a $C-H$ $\sigma$ bond.
The two unhybridized $2p$-orbitals of each carbon atom undergo sidewise overlap,forming two $\pi$-bonds. Thus,the triple bond consists of one $\sigma$ and two $\pi$-bonds.