Multiple choice

When upper surface of a lake is freezed, the temperature of the water beneath it is _________.

  1. <span style="font-family:" arial;="" font-size:="" small;="">less than 4<sup style="font-family:" arial;="">°<span style="font-family:" arial;="" font-size:="" small;="">C

  2. <span style="font-family:" arial;="" font-size:="" small;="">0<sup style="font-family:" arial;="">°<span style="font-family:" arial;="" font-size:="" small;="">C

  3. 4°C

  4. more than 4°C
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Water has maximum density at 4°C. When a lake freezes from the top, the ice layer insulates the water beneath. The water at the bottom remains at approximately 4°C because this is the temperature at which water is densest and sinks. The water below the ice doesn't reach 0°C or below because the ice acts as an insulator.

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