(a) Draw a structural formula for C₂H₄.

(b) Draw the trans isomer of C₂H₂Cl₂.

The structural formula shows the arrangement of atoms in a compound molecule, drawing from its molecular formula.

Trans isomers are molecules with the same molecular formula but different structural formulae in which the same atoms are on the opposite side.

The carbon atom can share four electrons with the other atoms to complete its octet. It usually binds to another carbon atom through a covalent double bond structure.

A sharing of two electrons is indicated by a straight line in the structure. So, the presence of two double bonds will contain electrons equal to four single bonds.

a. C₂H₄: The two carbon atoms bind to each other by a double bond. Hydrogen atoms fill the remaining free ends.

b. C₂H₂Cl₂: Two carbon atoms bind by double bonds. Two chlorine atoms get attached to two carbon atoms on the trans side (opposite to each other). Hydrogen atoms fill the free ends.