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Q26
(NDA-I/2008)
Science & Technology › Basic Science (Physics, Chemistry, Biology) › Thermal physics
Answer Verified
When water is heated from 0°C to 20°C, how does its value change?
Result
Your answer:
—
·
Correct:
D
Explanation
The correct answer is Option 4 because water exhibits a unique physical property known as anomalous expansion between 0°C and 4°C.
Typically, liquids expand when heated. However, when water is heated from 0°C, its density increases and its volume decreases until it reaches 4°C, where it attains its maximum density. Beyond 4°C, water behaves normally; as the temperature continues to rise toward 20°C, the molecular motion increases, causing the volume to increase.
- 0°C to 4°C: Volume decreases (Density increases).
- 4°C to 20°C: Volume increases (Density decreases).
Therefore, the volume first decreases and then increases. Option 1 is incorrect as it ignores the contraction phase; Option 2 is incorrect as it ignores expansion after 4°C; and Option 3 is the exact opposite of water's actual behavior.
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