Which one of the following is a compound?

Options

A. Glass
B. Water gas
C. CNG
D. Plaster of Paris

Answer

To determine which of the given options is a compound, we need to analyze each option based on the definition of a compound. A compound is a substance formed when two or more different types of atoms bond together in a fixed ratio.

### Step-by-Step Solution:

1. **Identify the Options**:
- Option A: Glass
- Option B: Water gas
- Option C: CNG (Compressed Natural Gas)
- Option D: Plaster of Paris

2. **Analyze Each Option**:
- **Option A: Glass**: Glass is primarily made of silica (SiO2) and may contain other components, but it is generally considered a solid mixture rather than a pure compound.

- **Option B: Water gas**: Water gas is a mixture of carbon monoxide (CO) and hydrogen (H2). Since it consists of more than one type of molecule, it is classified as a mixture.

- **Option C: CNG (Compressed Natural Gas)**: CNG mainly consists of methane (CH4) but can also contain other hydrocarbons like butane, ethane, and propane. Since it is a mixture of different gases, it is not a pure compound.

- **Option D: Plaster of Paris**: The chemical formula for Plaster of Paris is CaSO4·1H2O. It is composed of different types of atoms: calcium (Ca), sulfur (S), oxygen (O), and hydrogen (H). Since it is made up of different elements that are chemically bonded in a fixed ratio, it qualifies as a compound.

3. **Conclusion**: Among the options provided, **Option D: Plaster of Paris** is the only compound.

### Final Answer:
**The compound among the options is Plaster of Paris (Option D).**

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