Which of the following represents the heavy water?

Options

A. water at `277 k`
B. water contaning large contamination of lead salts
C. deuterium oxide
D. protium oxide

Explanation

To determine which of the following represents heavy water, we need to understand what heavy water is.

### Step-by-Step Solution:

1. **Definition of Heavy Water**: Heavy water is a form of water that contains deuterium, which is an isotope of hydrogen. Unlike ordinary water (H₂O), which contains protium (the most common hydrogen isotope), heavy water is represented as D₂O.

2. **Understanding Isotopes**: Deuterium (D) has one neutron in addition to the one proton in its nucleus, giving it a greater mass compared to protium (which has no neutrons). Therefore, heavy water (D₂O) has a higher molecular weight than ordinary water.

3. **Analyzing the Options**:
- **Option A**: Water at 277 Kelvin - This option refers to the temperature of water, which does not determine whether it is heavy or light water. Therefore, this option is incorrect.
- **Option B**: Water containing large contamination of lead salt - The presence of lead salt does not relate to the composition of water in terms of hydrogen isotopes. This option is also incorrect.
- **Option C**: Deuterium oxide (D₂O) - This is the correct representation of heavy water, as it specifically indicates the presence of deuterium instead of protium.
- **Option D**: Protium oxide - This refers to ordinary water (H₂O), which is not heavy water. Hence, this option is incorrect.

4. **Conclusion**: Based on the analysis, the correct answer is **Option C: Deuterium oxide (D₂O)**.

### Final Answer:
The heavy water is represented by **D₂O** (Deuterium oxide).