When water is dropped over sodium peroxide, the colourless gas produced is

Options

A. dinitrogen
B. dioxygen
C. dihydrogen
D. hydrogen peroxide

Explanation

To solve the question, "When water is dropped over sodium peroxide, the colourless gas produced is," we can follow these steps:

### Step 1: Identify the Reactants
The reactants in this reaction are sodium peroxide (Na2O2) and water (H2O).

### Step 2: Write the Reaction
When sodium peroxide reacts with water, the following reaction occurs:
\[ \text{Na}_2\text{O}_2 + 2 \text{H}_2\text{O} \rightarrow 2 \text{NaOH} + \text{H}_2\text{O}_2 \]

### Step 3: Identify the Products
From the reaction, we see that sodium hydroxide (NaOH) and hydrogen peroxide (H2O2) are produced.

### Step 4: Analyze Hydrogen Peroxide
Hydrogen peroxide (H2O2) is known to be unstable and can decompose. The decomposition reaction is:
\[ 2 \text{H}_2\text{O}_2 \rightarrow 2 \text{H}_2\text{O} + \text{O}_2 \]

### Step 5: Identify the Colourless Gas
From the decomposition of hydrogen peroxide, we see that oxygen gas (O2) is produced, which is a colourless gas.

### Conclusion
Thus, when water is dropped over sodium peroxide, the colourless gas produced is di-oxygen (O2).

### Final Answer
The correct answer is: **Di-oxygen (O2)**.

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