Weathering is the breaking down or dissolving of rocks and minerals on Earths surface. Once a rock has been broken down, a process called erosion transports the bits of rock and minerals away. Water, acids, salt, plants, animals, and changes in temperature are all agents of weathering and erosion
Answer:
1: At temperatures below 542.55 K
2: At temperatures above 660 K
Explanation:
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In this case, according to the thermodynamic definition of the Gibbs free energy, it is possible to write the following expression:

Whereas ΔG=0 for the spontaneous transition. In such a way, we proceed as follows:
1:

It means that at temperatures lower than 542.55 K the reaction will be spontaneous.
2:

It means that at temperatures higher than 660 K the reaction will be spontaneous.
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You have to think about the fact that hot air is constantly being blown up elevating the balloon once that air is taken away it's up to the steering and the wind after that. I know that probably doesn't help did you want to know the science part?