Different elements emit different spectra when their electrons get excited because each element has a different arrangement of electrons surrounding the nucleus. The energy levels in which the electrons can occupy are unique to a specific element. When an electron gets excited into a higher energy level, it will eventually relax back into its original state and emit light corresponding to that energy.
Cell theory states that all the living organisms are made up of basic structural and functional units, cells. All cells divide and give rise to new cells. All the cells have similar chemical composition. The nuclei acid DNA present in the chromosomes helps in carrying hereditary information from generation to generation. So, in order to sustain life the cells must contain DNA either enclosed in the nucleus or freely floating in the cytoplasm.
Answer:
<h3>I think, answer is threshold energy.</h3>
OR
<h3>activation energy. </h3>
Explanation:
<h3>Hope it helps you....</h3>
<h2>Thank you..</h2>
