Which of the following gases can be used for storage of fresh sample of an oil for a long time?

Options

A. Carbon dioxide or oxygen
B. Nitrogen or oxygen
C. Carbon dioxide or helium
D. Helium or nitrogen

Explanation

To determine which gases can be used for the long-term storage of fresh samples of oil, we need to consider the properties of certain gases and their effects on the oil.

### Step-by-Step Solution:

1. **Understanding the Problem**: We need to find gases that can help in storing fresh oil without causing it to spoil. Spoilage often occurs due to oxidation, which can lead to rancidity.

2. **Identifying Relevant Gases**: The gases that are commonly considered for creating an inert atmosphere are Helium and Nitrogen. These gases are known for their unreactive nature.

3. **Properties of Helium and Nitrogen**:
- **Helium**: It is a noble gas, which means it does not react with other substances. This property helps in preventing oxidation.
- **Nitrogen**: It makes up a significant portion of the Earth's atmosphere and is also unreactive under normal conditions. It can displace oxygen in the storage environment.

4. **Role of Inert Atmosphere**: By using Helium or Nitrogen, we can create an inert atmosphere around the oil. This means that there is little to no oxygen present, which is crucial because:
- **Prevention of Oxidation**: Without oxygen, the oil cannot undergo oxidation, which is the primary cause of rancidity.
- **Extended Shelf Life**: The oil remains fresh for a longer time without developing off-flavors or odors.

5. **Conclusion**: Therefore, the gases that can be used for the storage of fresh samples of oil for a long time are Helium and Nitrogen.

### Final Answer:
The correct gases for the storage of fresh oil samples are **Helium and Nitrogen**.

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