Compounds with the same molecular formula and the same type and number of bonds but different spatial arrangements are called

• A. Structural isomers
• B. Stereoisomers
• C. Isotopes
• D. Polymers

Answer: (A)

This describes stereoisomerism. When two molecules have the same molecular formula and the same types and numbers of bonds, but their atoms are arranged differently in three-dimensional space, they are stereoisomers. The connectivity (which atom is bonded to which) is the same, but the spatial orientation differs, giving distinct stereochemical forms such as enantiomers or diastereomers.

If the connectivity were actually different—meaning the atoms are linked in different orders—you’d have structural (constitutional) isomers. Isotopes vary in nuclear composition rather than bonding, and polymers are large repeating units made from smaller monomers, not different spatial arrangements of the same bonds.