Which elements make up the empty spce in the universe ?

Explain why electric current cannot exist if a current doesn't have a voltage source.

Hydrogen atoms are excited by a laser to the =4n=4 state and then allowed to emit. what is the maximum number of distinct emission spectral lines (lines of different wavelengths) that can be observed from this system? 8 6 2 7 4 5 1 3 calculate the wavelength of the 4⟶14⟶1 transition. =λ=

Which compound is held together by the electrostatic force between two ions? a. co2 b. cci4 c. h2s d. mgf2