Question

The correct `IUPAC` name of the compound shown below

A. spiro`[4,3]` octane
B. spiro `[3,4]` octane
C. spiro `[4,5]` octane
D. cyclobutyl cyclopentane

Answer 1

Correct Answer - b
If only one carbon is common between two rings, compound comes in spirane family.
The name here has prefix spiro followed by number of carbons in two rings `(` excluding common carbon `).`

Numbering start from smaller ring. Hence, name is spiro `[3,4]` octane.