3) The spectrum of the unknown mixture is a mixture of two substances among the five. What are these two substances

a. H + d. Na

Explanation:

This is Mixture of H and Na. Because of H and in the emission and Absorption spectrum of H Total 5 lines [Red, Green, Blue and Purple (2)) are present and in the spectrum of Na Two yellow lines are present. In the mixture all this lines are are also 5 + Present. Total lines are 5+2= 7 (H+ Na)

Therefore, the answer is a. H + d. Na