ACT science practice test 61

Directions: Each passage is followed by several questions. After reading a passage, choose the best answer to each question and fill in the corresponding oval on your answer document. You may refer to the passages as often as necessary.

You are NOT permitted to use a calculator on this test.

Two investigations were conducted on a sample of green nickel sulfate (NiSO4) that was dissolved in water. The first investigation placed a sample of the nickel sulfate into a spectrometer. Most solutions absorb some wavelengths of light and allow other wavelengths to pass right through. The spectrometer changed the wavelength of light shining into the solution and recorded how much of the light was absorbed by the solution. An absorbance of 0.00 would indicate that all of the light shone into the solution passed through with no light being absorbed. Figure 11.4 shows the result of absorbance versus wavelength for a sample of NiSO4(aq).

Figure 11.4

The next experiment used five different solutions of NiSO4(aq) at different known concentrations (measured in molarity). Each solution was placed in a spectrometer set at 740 nm, and light was shone into each sample to determine the absorbance of each of the five solutions. Table 11.3 shows the results.

TABLE 11.3

1. Which wavelength of light was absorbed to the greatest degree in the first investigation?

A. 380 nm
B. 500 nm
C. 740 nm
D. 830 nm

2. The wavelength of 490 nm is green light. Why is the absorbance of NiSO4 low at 490 nm?

A. The spectrometer is not accurate at the wavelength of 490 nm.
B. The NiSO4(aq) is green in color, so green light from the spectrometer passes through the solution.
C. The NiSO4(aq) is green in color, so the green light from the spectrometer is absorbed to a large extent.
D. The green light gets reflected back to the spectrometer when it contacts the green NiSO4(aq) solution.

3. What conclusions can be drawn from the data collected in Table 11.3?

A. As the wavelength of light aimed at the sample increases, the absorbance increases.
B. Light with a wavelength of 740 nm is not absorbed to a great extent by NiSO4(aq).
C. Concentration of solution is inversely proportional to absorbance of light.
D. As the concentration of NiSO4(aq) increases, the absorbance of light increases.

4. Which of the following statements accurately describes the trend found in Table 11.3?

A. Light with a wavelength of 740 nm increases absorbance by about 0.09.
B. Doubling the concentration of NiSO4(aq) causes an increase in absorbance of about 0.90.
C. An increase of 0.08 mol/L causes an increase in the absorbance of about 0.90.
D. The absorbance of NiSO4(aq) stops increasing at a concentration of 0.40 mol/L.

5. Which set of data would best represent the results if Investigation 2 were repeated with a wavelength of 490 nm instead of 740 nm?



6. The process of spectrometry works well on colored solutions such as green nickel sulfate (NiSO4) and cupric sulfate (CuSO4). Why might spectrometry not work well on solutions such as table salt dissolved in water (NaCl(aq))?

A. Table salt is clear, so it will absorb all wavelengths of light.
B. Table salt is clear, so all colors of light will pass through the solution.
C. The researcher cannot vary the concentration of table salt.
D. Spectrometry is not appropriate for food-grade substances.

7. Experiment 2 was repeated with a sixth sample of NiSO4 solution with a concentration of 0.48 mol/L. However, the test tube had fingerprints on the glass where the light passed through. The fingerprints absorbed some light from the spectrometer. What would be an expected value for the absorbance?

A. 0.451
B. 0.522
C. 0.542
D. 0.622

8. What would be the results of Investigation 1 if a more concentrated solution of NiSO4(aq) were used to make the graph in the table?

Figure 11.5
Figure 11.6
Figure 11.7
Figure 11.8