D. Electrons orbit in a fixed shell
Answer:
Atomic emission spectrum came out by a series of colored lines
Explanation:
When electricity is passing through an element or when it is viewing through a prism, a unique spectra of light emitted by an element is called atomic emission spectra. They are acting as an element of finger print because they are unique. When we are seeing a set of colored lines or a black background , it is an emission spectrum. If we are watching black lines on a colored background it is absorption spectrum. In electromagnetic spectrum the visible portion are the colors.
In nucleus electrons can exist in some areas are known as shells. Shell corresponds an energy level that is designed by a quantum number n. The lowest energy level electrons are close to the nucleus.
An atom is shone by light, its electrons absorbs photons and it gain energy, and jump to higher level.
Astronauts use "Astronomical Unit" to measure the distance between planets in our solar system "only". To measure long distances like between 2 galaxies, they use "light years". One Astronomical Unit = Average distance between sun and earth which is equal to 149.6 million kilometers. Ping me if you have any doubt.
That’s ez that’s 1st grade math the answer is none
