How do electrons enter an orbital

Electrons that occur together in an orbital are called an electron pair. An electron will always try to enter the orbital with the lowest energy. ... In other words, within one energy level, electrons will fill an s orbital before starting to fill p orbitals. The s subshell can hold 2 electrons.

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answer: c. the experiment shows that the red substance experienced a chemical change.

explanation: chemical change is the change in which chemical composition of the substance changes. physical change is the change in which there is no change in chemical composition.

chemical changes are accompanied by following changes:

a) precipitate formation

b) energy is released or absorbed

c) formation of bubbles

d) change in color

as it is given that the red color has disappeared and there is production of gas, it means the red substance has undergone a chemical change.

e