Observe the figure and answer the questions given below.[Figure: a block of ice resting on a wooden stand; a thin wire passes over the ice with two heavy weights hanging from its ends; the wire has cut through the ice but the ice above it has frozen…

Answer: (a) Regelation; (b) the melting of ice under pressure and its refreezing when the pressure is removed.

(a) The phenomenon is regelation.

(b) When pressure is applied on ice, its melting point decreases, so the ice under the wire melts even below 0 ºC. As the wire moves down, the water above it is no longer under pressure and freezes again, so the wire passes through the block without cutting it into two pieces. This melting under pressure and refreezing on release of pressure is called regelation.