Name the gas which is colourless, odourless, tasteless, combustible, lighter than air and insoluble in water.

Options

A. Steam
B. Oxygen
C. Nitrogen
D. Dihydrogen

Answer

To solve the question, we need to identify the gas that meets the following criteria:

1. Colorless
2. Odorless
3. Tasteless
4. Combustible
5. Lighter than air
6. Insoluble in water

### Step-by-Step Solution:

**Step 1: Analyze the properties of the gases.**
- We need to consider gases that are known to be colorless, odorless, and tasteless.

**Step 2: Evaluate the first option - Steam.**
- Steam is indeed colorless, odorless, and tasteless, but it is not combustible. Therefore, it does not meet all the criteria.

**Step 3: Evaluate the second option - Oxygen.**
- Oxygen is colorless, odorless, and tasteless, and it is combustible (supports combustion). However, it is heavier than air, which disqualifies it from being the correct answer.

**Step 4: Evaluate the third option - Nitrogen.**
- Nitrogen is colorless, odorless, and tasteless, but it is non-combustible (an inert gas). Thus, it does not satisfy the requirement of being combustible.

**Step 5: Evaluate the fourth option - Dihydrogen.**
- Dihydrogen (H₂) is colorless, odorless, tasteless, combustible, lighter than air, and insoluble in water. It meets all the criteria mentioned in the question.

**Step 6: Conclusion.**
- The gas that fulfills all the conditions is dihydrogen.

### Final Answer:
The gas which is colorless, odorless, tasteless, combustible, lighter than air, and insoluble in water is **Dihydrogen (H₂)**.

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