Can someone help please help me hel which material would make the least efficient heat sink

material: heat capacity:

pure water 4.18
seawater 3.89
dry air 1.00
wet mud 2.51
brick 0.84
granite 0.79
limestone 0.92

Ican determine the molar mass of an element by looking on the under the atomic mass for the element. for example the molar mass of phosphorus is 30.974 grams/mole. avogadro’s number tells me the amount of representative particles in 1 mole of any substance. this means 12.011 gram sample of carbon and a 32.0 gram sample of sulfur have the same number of atoms.