Which of the following is neither an element nor a compound?

Options

A. Air
B. Water
C. Mercury
D. Sodium chloride

Answer

To determine which of the following options is neither an element nor a compound, we need to analyze each option based on the definitions of elements, compounds, and mixtures.

### Step 1: Understand the Definitions
- **Element**: A pure substance that cannot be broken down into simpler substances by chemical means. It consists of only one type of atom.
- **Compound**: A substance formed when two or more different types of atoms chemically bond together in fixed proportions.
- **Mixture**: A combination of two or more substances that are not chemically bonded and can be separated by physical means.

### Step 2: Analyze Each Option
- **Option A: Air**
- Air is a mixture of various gases, including nitrogen, oxygen, argon, carbon dioxide, and others. Since it consists of multiple types of substances that are not chemically bonded, it is classified as a mixture.

- **Option B: Water (H2O)**
- Water is a compound made from two different types of atoms: hydrogen and oxygen. It has a fixed ratio of 2 hydrogen atoms to 1 oxygen atom, so it is not a mixture.

- **Option C: Mercury (Hg)**
- Mercury is an element. It consists of only one type of atom and cannot be broken down into simpler substances, so it is not a mixture or a compound.

- **Option D: Sodium Chloride (NaCl)**
- Sodium chloride is also a compound. It consists of sodium and chloride ions bonded together in a fixed ratio, so it is not a mixture.

### Step 3: Conclusion
Based on the analysis, the only option that is neither an element nor a compound is **Option A: Air**, as it is a mixture of various gases.

### Final Answer
**The correct answer is Option A: Air.**

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