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எங்கள் ஆசிரியர்களுடன் 1-ஆன்-1 ஆலோசனை நேரத்தைப் பெறுங்கள். டாப்பர் ஆவதற்கு நாங்கள் பயிற்சி அளிப்போம்

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1. Why does the bottom of a lake not freeze in severe winter though the surface is all frozen?
  
Due to the comparatively  of the water at the bottom and  of the ice keeps the lakes unfrozen at the bottom.
 
Reasons:
 
Pressure is  to the temperature at the bottom of a water body is  compared to the pressure at the surface. Due to the  at the bottom, the temperature at the bottom of the lake is comparatively .
 
Ice is  than water; thus, it floats on the surface of the water, and it  at the bottom of the lake.

2. Which one of the following statements about thermal conductivity is correct?
  

Reason:
 
Steel is a  due to the  to conduct the heat in the form of kinetic energy.
 
Water is a  as first water .
 
Wood has the  because of the  of the wood.