The temperature of water at the bottom of a lake whose upper surface has frozen to ice would be around (in degrees Celsius)

Question

The temperature of water at the bottom of a lake whose upper surface has frozen to ice would be around (in degrees Celsius)

1. A. −10
2. B. 0
3. C. 4 (Correct answer)
4. D. −4

Correct Answer

Option C — 4

Detailed Solution & Explanation

The correct answer is 4.

Key Points

• Water at the bottom of a frozen lake is approximately 4°C because water has maximum density at 4°C. When the surface water cools below 4°C, it becomes less dense and stays on top (eventually freezing), while the denser 4°C water sinks to the bottom.
• This property, called anomalous expansion, protects aquatic life in freezing conditions.