Answer: sodium
Explanation: Because each element has an exactly defined line emission spectrum, scientists are able to identify them by the color of flame they produce. For example, copper produces a blue flame, lithium and strontium a red flame, calcium an orange flame, sodium a yellow flame, and barium a green flame.
Based on the flame test, the gaseous element which is present in street lights is sodium.
Spectrum is a table or a chart in which intensity of the emitted lights are showing over a range of species.
Each element show different color of spectrum in the emission process, whenever excited element emitted enegy then released energy is shown in the form of color spectrum. In traffic lights sodium lamps are present which in the presence of heat gets excited and changes to the gas form and emitted yellow color light.
Hence sodium gaseous element is present in street lights.
To know more about emission spectrum, visit the below link:
https://brainly.com/question/1287643
