Hey there!
Your answer is D. salt water
A mixture has more than one substance.
Salt water is made up of multiple different substances, salt (NaCl) and water (H₂O).
Carbon dioxide (CO₂), water vapor (H₂O), and oxygen gas (O₂) are each just one substance.
Hope this helps!
The color emitted be larger atoms is lower in energy then the light emitted by smaller atoms
B
When frequency increases, as does the energy, but wavelength decreases. It also works vise versa; if wavelength were to increase, its frequency and energy will decrease.
