Please help urgent How can you safely turn on and off an electromagnet on and off?

The correct answer should be "electrons orbit the nucleus in circular motions exactly as shown on the classic bohr model."

The answer to this is the 3rd choice!

Answerδh > 0explanationc₆h₆  (s)  → c₆h₆ (l)if you are changing it from a solid to a liquid, you are pretty much melting the solid. this requires heat energy. therefore, the reaction is endothermic (takes in energy); the system enthalpy increases as the reaction proceeds: δh > 0.