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.

answer: -

reaction:

na + cl ⇌ nacl

balanced chemical equation:

na + 2cl ⇌ nacl2

sodium + clorine goes to form sodium chloride (table salt).

the product is nacl2.

and the reactants are na and cl.

(note: if you don’t know what ⇌ means, read below: -

⇌(double head arrow) means reversible reaction).