Which substance would retain the most heat for the longest period of time?

Specific heat is defined as the amount of heat one gram of a substance must absorb or lose to change its temperature by one degree Celsius.

Explanation:

but capacity heats of material can be hold another unit  and either materials  (volume , mass)  somethings like how ,capacity heat compare to the materials or can be molybdenum ,or but the better  insulations or any heat  energy and also take a long time to heats up of materials

practical process described pest part of scientific investigation.

because practical knowledge is powerful then therotical knowledge.