1) An atomic absorption spectrometer can be used to determine the level of copper in soils. The calibration curve below plots the absorbance of four standard copper solutions against the concentration of copper ions in ppm.
The concentrations of copper ions in the standard solutions were 1.0, 2.0, 3.0 and 4.0 mg L^–1. (1 mg L^–1 = 1 ppm)

The concentration of copper in a test solution can be determined most accurately from the calibration curve if it is between
A. 0.0 ppm and 5.0 ppm.
B. 0.0 ppm and 4.0 ppm.
C. 1.0 ppm and 4.0 ppm.
D. 1.0 ppm and 5.0 ppm.

Solution

b) If the test solution gave an absorbance reading of 0.40, what would be the concentration of copper ions in the solution
in mol L^–1?
A. 2.5
B. 3.9 × 10–2
C. 3.9 × 10–5
D. 2.5 × 10–6

Solution