Question

Explain why the presence of spectral lines of a given element in the solar spectrum tells you that the element is present in the Sun, but the absence of the lines would not necessarily mean the element is absent from the Sun.

a. Some elements have a concentration in the Sun too low to emit or absorb light.

b. The gas may be too hot or too cool, or of the wrong density, for that type of atom to have electrons in the right energy levels to produce significant spectral lines.

c. Some elements at the temperature of the photosphere are entirely transparent and cannot interact with the electromagnetic waves.

Answer 1

The presence of spectral line is due to the transition between two states which is specific for a particular material, and hence they can be used to identify the element.

Whereas the absence of a spectral line could be because the conditions required for the transition are not present rather than the element being not present altogether.

So the best explanation in accordance with the given statement is provided by (b).