- Take some water in a glass vessel. Look carefully at the inner surface of the vessel.
- There are tiny bubbles on the inside of the vessel. These bubbles come from the air dissolved in water.
- Heat the water slowly on a tripod stand.
- We see the air dissolved in it escapes. On further heating, the water itself turns into vapour and finally begins to boil.
Thus, the animals living in water use the dissolved oxygen in water.
