Which substance is stored in contact with water to prevent if from reacting with air?

Options

A. Bromine
B. Lithium
C. Mercury
D. Phosphorus

Answer

To answer the question, "Which substance is stored in contact with water to prevent it from reacting with air?", we can follow these steps:

### Step 1: Identify the Substances
We need to consider which substances are known to react with air. Common substances that react with oxygen in the air include phosphorus, lithium, bromine, and mercury.

### Step 2: Analyze the Reactivity
Among the listed substances, phosphorus is particularly known for its reactivity with oxygen. When phosphorus is exposed to air, it can react with oxygen to form oxides, specifically P4O6 and P4O10, depending on the availability of oxygen.

### Step 3: Understand the Storage Method
To prevent phosphorus from reacting with oxygen in the air, it is stored in water. This is because water acts as a barrier, preventing phosphorus from coming into contact with air and thus inhibiting its oxidation.

### Step 4: Conclusion
Based on the analysis, the substance that is stored in contact with water to prevent it from reacting with air is **phosphorus**.

### Final Answer:
Phosphorus is stored in contact with water to prevent it from reacting with air.

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