Only 11% of all the energy used in the US comes from a renewable source. Why is this a
problem?

Fossil fuels and unnatural energy sources still dominate in the US, this influences many problems including global warming, climate change, and pollution. Burning fossil fuels is also a problem to human health. And unnatural resources won’t be there forever whereas, renewable sources could last a long time.

Determine the  wavelength of light emitted when an electron  in an li2+ ion  makes a transition from an orbital with n  =  6 to an orbital with n  = 5.