Context: For reasons that remain obscure, the planet's thermosphere is at an anomalously high temperature of about 750 K. The planet is too far from the Sun for this heat to be generated by ultraviolet radiation. One candidate for a heating mechanism is atmospheric interaction with ions in the planet's magnetic field. Other candidates are gravity waves from the interior that dissipate in the atmosphere. The thermosphere contains traces of carbon dioxide and water, which may have been deposited from external sources such as meteorites and dust.

Question: What is Neptune's temperature in the thermosphere? 
Answer: 750 K

Question: What would interact with Neptune's magnetic field to make it warm?
Answer: atmospheric interaction with ions

Question: Where would gravity waves in Neptune's interior dissipate? 
Answer: in the atmosphere

Question: What does Neptune's thermosphere containers traces of? 
Answer: carbon dioxide and water

Question: What is Uranus's temperature in the thermosphere?
Answer: Unanswerable

Question: What would interact with Neptune's magnetic field to make it cold?
Answer: Unanswerable

Question: Where would gravity waves in Neptune's interior appear?
Answer: Unanswerable

Question:  What does Neptune's thermosphere never contain traces of?
Answer: Unanswerable