Ordinary oxygen contains.

Options

A. A mixture of `O^(16), O^(17)` and `O^(18)`
B. A mixture of `O^(16)` and `O^(17)`
C. Only `O^(16)`
D. Only `O^(18)`

Answer

To answer the question "Ordinary oxygen contains," we need to analyze the isotopes of oxygen and their characteristics. Here’s a step-by-step solution:

### Step 1: Understanding Ordinary Oxygen
Ordinary oxygen, often referred to as molecular oxygen (O2), is the form of oxygen that we commonly encounter in the atmosphere. However, it is important to note that ordinary oxygen is not just a single type of atom; it consists of isotopes.

**Hint:** Think about what isotopes are and how they relate to the element oxygen.

### Step 2: Identifying Isotopes of Oxygen
Oxygen has three stable isotopes:
- Oxygen-16 (O-16)
- Oxygen-17 (O-17)
- Oxygen-18 (O-18)

These isotopes have the same atomic number (8) but different mass numbers (16, 17, and 18 respectively).

**Hint:** Recall the definition of isotopes: atoms of the same element with different mass numbers.

### Step 3: Composition of Ordinary Oxygen
When we refer to ordinary oxygen, we are actually talking about a mixture of these isotopes. The most abundant isotope is O-16, but O-17 and O-18 are also present in smaller amounts.

**Hint:** Consider the abundance of each isotope in nature.

### Step 4: Conclusion
Based on the information gathered, we can conclude that ordinary oxygen contains a mixture of the isotopes O-16, O-17, and O-18. Therefore, the correct answer to the question is that ordinary oxygen contains these three isotopes.

**Hint:** Summarize the key points about the isotopes and their significance in defining ordinary oxygen.

### Final Answer
Ordinary oxygen contains a mixture of isotopes O-16, O-17, and O-18.