Question

Write scientific reason.

Fish can survive even in frozen ponds in cold regions.

Answer 1

1. In cold climate, temperature of water in ponds and lakes starts falling.
2. On getting colder, water contracts. As a result, the density of water increases and it goes down. To replace it, warmer water from below rises up. This process continues till temperature of water at the bottom of pond becomes 4 °C.
3. Water, due to its anomalous behaviour possesses maximum density at 4 °C.
4. If the temperature lowers further, ice is formed at the surface of a pond with water below it.
5. Ice is a poor conductor of heat blocks the further heat exchange between the atmosphere and water in the pond.
6. This prevents freezing of water below surface of ponds or lakes enabling survival of fishes.