How can i use 'spectral line'

'energy level'

and 'electron cloud' in scientific sentences?

You could search on line or in an actual book and find out what they mean,

then write a sentence with a very simple definition or explanation of each one.

As an electron changes from a high energy level to a low energy level it emits a photon at a frequency associated with E=hf where E is the energy difference, h is planks constant and f is the frequency of the photon. Each photon emitted from the change in energy states is then ejected from the electron cloud in a random direction and can be noted as the atoms emission spectral line when observed.