What must happen for an electron to move to a higher energy level?
o
the electron must gain energy
o
the electron must transfer energy to another electron.
the electron must release energy through fission.
o
the electron must collide with the nucleus.

The electron must gain energy.

Explanation:

For a electron to be promoted from one energy level to a higher energy level it has to absorb energy. If the electron decay back to the initial energy level will emit a photon with the a energy equal of the difference between the two energetic levels.

they are made of gases.

they have a spherical shape.

they make energy through fusion.