Final answer:
Emission spectroscopy uses unique spectral lines to identify elements, and strontium, an Alkaline Earth Metal, can be identified by its distinct lines. Without the chart data, the correct set of elements cannot be chosen, but the principles of spectroscopy allow identification of elements, even in distant stars.
Step-by-step explanation:
To determine which set of elements is present on the nearby planet using emission spectroscopy, one would compare the observed spectral lines with those of known elements. Emission spectra provide unique 'fingerprints' for each element. Based on the information given, strontium is one of the elements to look for since it belongs to the Alkaline Earth Metals, specifically in the same group as calcium. Furthermore, if the emission spectrum on the chart matches the unique lines of strontium, this would confirm its presence on the planet. Similarly, sodium also has a distinct emission spectrum that can be used for identification. Without the emission spectrum chart data, it is impossible to accurately determine which set of elements is correct. However, if students were provided with both the spectra and the chart, they could match spectral lines to the listed elements to make an informed decision.
Regarding the second part of the question, it is indeed possible to identify an element from a single spectral line if that line is unique to the element. Scientists rely on the atomic emission spectrum to identify elements in distant stars by matching the observed lines to known spectra of elements. For example, hydrogen has a specific set of lines that, if observed in a star's light, would indicate the presence of hydrogen.