From the ideal gas equation,

where n is number of moles, R is Universal gas constant, P is pressure, V is volume, and T is temperature of the gas.
The pressure and volume are inversely proportional to each other at constant temperature and number of moles.
Hence, on decreasing the pressure, the volume will increase.
As the hiker reaches a height of a mountain, the pressure would decrease which results in the reestablishment of equilibrium between gas molecules thus resulting in pushing of bag outwards.
Hence, the bag will expand as the hiker reaches the top of the mountain.
A mole is a unit to describe an amount of something/specific substance. Typically standard for measuring a large quantity of small entities like atoms, molecules, or other particles.
Answer: what is the question
Answer:
This question is incomplete
Explanation:
This question is incomplete because the result of the described experiment would have better determined the type of scientific explanation to profer. However, the type of material that will preserve the relative hotness or temperature of the hot coffee for the longest time will be a material than can resist heat transfer. These materials tend to keep hot substances hot by not allowing the heat of the coffee to be conducted or pass through it. These materials are mostly insulators or made by placing an insulator between two heat conductors.
Generally, heat is usually transferred from a region of higher concentration to a region of lower concentration, hence when the heat is denied of this transfer, the heat will remain trapped in the "heat-donor" substance (in this case the hot coffee). Thus, the material chosen (A, B or C) will be the material that resists heat transfer the most based on the explanation above.
I believe the best answer to that question wud be D. I cud b wrong