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Q49 (CDS-I/2006) Science & Technology › Basic Science (Physics, Chemistry, Biology) › Thermal physics Answer Verified

Assertion (A): It is possible to fuse two ice cubes by pressing them together. Reason (R): Pressure affects the melting point of a solid

Result
Your answer: —  Â·  Correct: A
Explanation

Assertion (A) is true because two ice cubes can be fused by pressing them together, a phenomenon known as regelation [t2][t7]. Reason (R) is also true and provides the correct explanation for (A). For most substances, increasing pressure raises the melting point; however, ice is an exception [c5]. According to the Clausius-Clapeyron equation, because ice is less dense than liquid water, an increase in pressure lowers its melting point [t6][t10]. When two cubes are pressed, the pressure at the contact interface lowers the melting point below the ambient temperature, causing a thin layer of ice to melt into water [t1][t9]. Once the pressure is released, the melting point returns to its normal value (0°C), and the water film refreezes, effectively welding the two cubes together [t7][t9].

Sources

  1. [1] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 4: Earths Interior > UPSC Prelims 2009] In the structure of planet Earth, below the mantle, the core is mainly made up of which one of the following? > p. 56
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SIMILAR QUESTIONS

CDS-I · 2002 · Q50 Relevance score: 0.96

When two icecubes are pressed together, they join to form one cube. Which one of the following helps to hold them together?

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Why do two ice blocks join to form one block when pressed together?

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Assertion (A) : Butter softens at room temperature. Reason (R) : Short chain fatty acids cause the melting point to decrease.

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