Answer : The ice at
is an exception to this rule.
Explanation :
We are given that with increase in temperature, the substance becomes less dense. But from the given options, the exception is Ice.
Ice is less dense than the liquid water because when water freezes down, the molecules arrange themselves in a cyclic manner and hence result in the expansion of water as it freezes.
When the temperature of the ice increases, it starts to melt and becomes water. The density of water is more than ice.
Hence, the correct answer is option C.