Which one of the following is applicable to the conformations of a hydrocarbon ?

Options

A. C- C distance changes
B. C-H distance changes
C. C-C-C and C-C-H bond angles change.
D. Only distance between non-bonded H-atoms changes

Answer

To solve the question "Which one of the following is applicable to the conformations of a hydrocarbon?", we need to analyze the conformations of hydrocarbons and their characteristics. Here’s a step-by-step breakdown:

### Step 1: Understand Hydrocarbon Conformations
Conformations refer to the different spatial arrangements of atoms in a molecule that can be interconverted by rotation around single bonds. For hydrocarbons, the most common conformations are staggered and eclipsed.

**Hint:** Remember that conformations are related to the rotation around single bonds in hydrocarbons.

### Step 2: Identify Types of Conformations
The main types of conformations include:
- **Staggered Conformation:** Atoms or groups are positioned as far apart as possible.
- **Eclipsed Conformation:** Atoms or groups are aligned with each other, leading to increased steric strain.

**Hint:** Visualize the staggered and eclipsed conformations to understand how atoms are arranged in space.

### Step 3: Analyze the Changes in Distance
When discussing conformations, we need to consider how the distances between atoms change:
- The distance between two bonded atoms (like C-C or C-H) remains constant during rotation.
- However, the distance between non-bonded atoms (like H-H) can change significantly between staggered and eclipsed conformations.

**Hint:** Focus on the distances between non-bonded atoms when considering changes in conformations.

### Step 4: Evaluate the Given Options
Based on the analysis:
- The distance between bonded atoms (C-C or C-H) does not change.
- The distance between non-bonded hydrogen atoms does change, particularly in the transition from staggered to eclipsed conformations.

**Hint:** Look for options that mention changes in distances between non-bonded atoms.

### Step 5: Conclude the Answer
The correct answer to the question is that the distance between two non-bonded hydrogen atoms changes during conformational changes in hydrocarbons.

**Final Answer:** The only distance that changes is the distance between two non-bonded hydrogen atoms.