Which of the following statements correctly describes $\mathrm{cis}-\mathrm{trans}$ isomers?

• A. $\mathrm{cis}-\mathrm{trans}$ isomers are identical in both molecular formula and spatial arrangement.
• B. $\mathrm{cis}-\mathrm{trans}$ isomers are a type of structural isomerism where atoms are connected differently.
• C. $\mathrm{cis}-\mathrm{trans}$ isomers have different molecular formulas and differ in the spatial arrangement of atoms around a double bond.
• D. $\mathrm{cis}-\mathrm{trans}$ isomers have the same molecular formula but differ in the spatial arrangement of atoms around a double bond.

Answer: (D)

Verified step by step guidance

1. Understand that isomerism refers to compounds with the same molecular formula but different arrangements of atoms.
2. Recognize that cis-trans isomerism is a type of stereoisomerism, not structural isomerism. Structural isomers have different connectivity of atoms.
3. Identify that cis-trans isomers specifically involve the spatial arrangement of groups around a double bond or a ring structure.
4. Note that in cis isomers, similar or identical groups are on the same side of the double bond, while in trans isomers, they are on opposite sides.
5. Conclude that cis-trans isomers have the same molecular formula but differ in the spatial arrangement of atoms around a double bond, which affects their physical and chemical properties.