Question

4
24. Describe the unique property of water in respect of its thermal expansion as compared
to other liquids. Explain, why aquatic animals living in a lake of very cold region do
not die in severe winter despite of frozen surface of lake?
अन्य द्रवों की तुलना में पानी में ऊष्मीय प्रसार के असामान्य गुण का वर्णन कीजिए। अत्यधिक ठंडे क्षेत्र में
स्थित एक झील में रहने वाले जलीय जन्तु अत्यधिक ठंड के दौरान ऊपरी सतह का पानी जमने पर भी क्यों नहीं
मरते हैं?

Answer 1

Answer:

Water shows anamolous (strange) behaviour between the temperature 0°c to 4 °c. This is also called as anamolous expansion of water. Normally when a liquid is cooled down its density goes in increasing and as a result volume decreases. But when water is cooled down and when it reaches the temperature of 4°c its density starts decreasing and its volume increases i.e. it expands. That is why this is called the anamolous expansion of water. Due to this property when even though the top layers of lakes or water bodies are covered with ice the water below stays in liquid form only and thus the aquatic animals and plants are able to survive there.