State which compound would be needed to make a chemical hot pack and cold pack, and what quantity of each compound would be needed.

1A. State which compound would be needed to make a chemical hot pack and cold pack, and what quantity of each compound would be needed.

1B.The same process, salts dissolving in water, is used to make both a hot pack and a cold pack. Explain why one compound dissolves exothermically, while the other salt dissolving is an endothermic process.