(a) CO₂

(b) O₂

(c) C₂H₄

(d) C₂H₂

Solution:

Option (c) is the answer.

The electronic configuration of the atoms:

C: 1s² 2s² 2p²

H: 1s¹

One sigma bond and one pi bond make up a double bond. We have a sigma bond in a single bond. So, in C₂H₄, two sp² hybrid orbitals from different carbon atoms unite to produce a sigma bond.

The pi bond is formed by the two carbon atoms’ 2p orbitals (unhybridized, either 2p_y or 2p_z). This results in the C=C double(=) bond.

As a result of the other sp² hybrid orbitals forming sigma bonds between C and H, the C-H single bonding structure is formed.