Which type of isomer has the same molecular formula but a different arrangement of atoms?

• A. Geometric isomer
• B. Optical isomer
• C. Structural isomer
• D. Titration

Answer: (C)

The situation describes structural isomers, which are compounds that have the same molecular formula but differ in the way their atoms are connected (the bonding pattern). That different connectivity means the atoms are arranged in a different skeletal framework or with different functional group placements, even though the formula is the same. Geometric isomers keep the same connections but differ in how groups are oriented in space around a double bond or ring (cis/trans). Optical isomers are stereoisomers that are non-superimposable mirror images due to chirality. Titration is a lab technique, not a type of isomer. So the best answer is the one that specifies a change in how atoms are linked within the molecule.