Structures which differ in configuration around C - 1 atom are called............

Explanation

To answer the question, "Structures which differ in configuration around C-1 atom are called...", we can break down the solution into a few clear steps:

### Step 1: Understanding the Concept of Isomers
Isomers are compounds that have the same molecular formula but different structural arrangements. There are various types of isomers, including structural isomers and stereoisomers.

**Hint:** Think about the different types of isomers and how they relate to molecular structure.

### Step 2: Identifying the Specific Type of Isomer
...