Q. Assertion: When hot water is poured in a beaker of thick glass, the beaker cracks.
Reason: Outer surface of the beaker expands suddenly.

 3062  194 AIIMSAIIMS 2009Thermal Properties of Matter Report Error

Solution:

When we pour hot water in beaker, the inner surface of the glass expands on heating. But heat from inside does not reach quickly the outer surface of the glass, because glass is a bad conductor of heat. Hence, the outer surface does not expand and the glass cracks.