Question

The bright light emission spectrums below are seen through a spectroscope. The unknown sample is a mixture of the observed gases.

5 rectangles labeled gas W, gas X, gas Y, gas Z and unknown sample. Gas W has 2 black lines left of center and 2 black lines close together right of center. Gas X has two black lines on the far left one on the far right and one on either side of center. Gas Y has one black line on either side of the center and one black line further right. Gas Z has one black line on the far left, one in the center and 2 on the right. The unknown sample has one black line on the far left, one in the center, one on either side of center and 2 on the right.

Which gases are found in the unknown sample?

gases W and Z
gases X and Y
gases W and Y
gases Z and Y

Answer 1

gases Z and Y

Reason: Z provides the far-left line, the center line, and two right-hand lines. Y provides the lines just either side of center (and a right-hand line that overlaps one of Z’s right lines), producing exactly the pattern seen in the unknown.