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

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