Cis- trans

Answer 1

Cis- and trans- are prefixes used to describe different types of isomers in chemistry.

Cis- refers to the arrangement of functional groups on the same side of a molecule. In a cis-isomer, the two substituents are on the same side of a double bond or ring.

Trans- refers to the arrangement of functional groups on opposite sides of a molecule. In a trans-isomer, the two substituents are on opposite sides of a double bond or ring.

These prefixes are mainly used to describe geometric isomers, which have the same molecular formula and connectivity but differ in the spatial arrangement of their atoms.