Question

Usha took a lump of dry soil in a glass and added water to it till it was completely immersed. She observed bubbles coming out. The bubbles contain:

• A. Water vapour
• B. Oxygen gas
• C. Air
• D. None of these

Answer 1

The correct option is C

Air

The correct option is C.

Explanation of the correct option:

1. On adding water to the soil, air bubbles were observed.
2. When the glass contained soil, the intermolecular spaces were filled with air.
3. Thus, when water was poured into it, the air escaped as bubbles.
4. This is so because, the soil being heavier than air, displaced it.
5. As a result, the upward displacement of air occurred as the water was poured into the soil.

Explanation of the incorrect options:

Option A:

Water vapor cannot be observed since the air inside the glass wasn't hot. Moreover, water vapor is heavy and wouldn't escape as bubbles. It forms droplets.

Option B:

Oxygen gas is a component of air and is not found in its pure form as it is highly flammable.

Final answer: Usha took a lump of dry soil in a glass and added water to it till it was completely immersed. She observed bubbles coming out. The bubbles contain air.