Which of the following structures represents a colourless substance

Options

A. `C_(6)H_(5) - N = underset(O)underset(|)(N) - C_(6)H_(5)`
B. `C_(6)H_(5) - N = N - C_(6)H_(5)`
C. `C_(6)H_(5)-NH - NH - C_(6)H_(5)`
D. None of these

Answer

To determine which of the given structures represents a colorless substance, we need to analyze the nature of the compounds based on their bonding and charge characteristics. Here’s a step-by-step solution:

### Step 1: Identify the Compounds
First, we need to look at the structures provided in the question. They are all nitrogen-containing compounds. We will analyze each one to see if they contain any features that would indicate color.

### Step 2: Understand the Role of Charge and Bonding
Color in chemical compounds often arises from the presence of charge transfer or unsaturated bonds (like double bonds). When there are double bonds or charges present, it can lead to electronic transitions that absorb visible light, resulting in color.

### Step 3: Analyze Each Compound
- **Compound 1**: If it has charges or double bonds, it is likely to be colored.
- **Compound 2**: Similar analysis; if it has unsaturation or charges, it may not be colorless.
- **Compound 3**: If it is a simple amine (like C6H5NH), with only single bonds and no charges, it is more likely to be colorless.

### Step 4: Conclusion
Based on the analysis, the compound that is likely to be colorless is the one with the formula **C6H5NH**. This compound has only single bonds and no charge transfer possibilities, making it colorless.

### Final Answer
The structure that represents a colorless substance is **C6H5NH**.

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