One of the following burns in air giving a gaseous oxide (at roon temp.)

Options

A. Hydrogen
B. Sodium
C. Sulphur
D. Helium

Explanation

To solve the question "One of the following burns in air giving a gaseous oxide (at room temp.)," we will analyze each option provided to determine which element produces a gaseous oxide when burned in air.

### Step-by-Step Solution:

1. **Identify the Options**: We need to consider the options provided (which are not listed here, but we will assume common elements such as hydrogen, sodium, sulfur, and helium based on the transcript).

2. **Analyze Option A: Hydrogen (H2)**
- When hydrogen burns in air, it reacts with oxygen to form water (H2O).
- **Chemical Reaction**: 2H2 + O2 → 2H2O
- Water is a liquid at room temperature.
- **Conclusion**: This option does not produce a gaseous oxide at room temperature.

3. **Analyze Option B: Sodium (Na)**
- When sodium burns in air, it reacts with oxygen to form sodium oxide (Na2O) and sodium peroxide (Na2O2).
- **Chemical Reaction**: 4Na + O2 → 2Na2O
- Both sodium oxide and sodium peroxide are solids or liquids at room temperature.
- **Conclusion**: This option does not produce a gaseous oxide at room temperature.

4. **Analyze Option C: Sulfur (S)**
- When sulfur burns in air, it reacts with oxygen to form sulfur dioxide (SO2).
- **Chemical Reaction**: S + O2 → SO2
- Sulfur dioxide is a gas at room temperature.
- **Conclusion**: This option produces a gaseous oxide at room temperature.

5. **Analyze Option D: Helium (He)**
- Helium is a noble gas and does not burn in air.
- **Conclusion**: This option does not produce any oxide.

6. **Final Conclusion**: Based on the analysis, the only element that burns in air to produce a gaseous oxide at room temperature is sulfur (option C).

### Final Answer:
**C) Sulfur**

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