Answer: Endothermic reaction.
Explanation: A chemical reaction in which energy is absorbed from the surrounding environment.
The helium would expand into the air of the room. Depending on how big the room is, and the amount of helium in the jar, it could cause damage to health. The only way this would happen is if the room was small and the jar was big.
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Net Primary Productivity ... the amount of biomass present in an ecosystem at a particular time .... Explain why a slow growing forest can have a very low NPP and yet store a massive amount of biomass.