Answer : Normally all molecular motions seizes at 0k which is -272oC so the temperature can't go below that
Step-by-step explanation:
But, the rocks cracked because of too much expansion. Generally at night, water can be found within rocks which then evaporates during the day. And when water is cold or freezed it expands. So, as the water in the rock expands it causes an increase in size until a certain level where it can no more expand, it cracks.What causes the split of the rock is due to the expansion of water as it freezes