Chapter 34 Multiple choice questions

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. An analyst determines the amount of contaminant in samples of steel as 1.0, 1.1, 1.3, 1.3, 1.4, 1.5, and 1.5 ppm.
What is the variance in ppm?

0.22 (to 4 s.f.) correct incorrect

−3.172 10⁻¹⁷ (to 4 s.f.) correct incorrect

1.69 (to 4 s.f.) correct incorrect

0.03143 (to 4 s.f.) correct incorrect

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. An analyst determines the concentration of a pathogen in an athlete's blood as 12.0, 13.1, 14.3, 16.3, 21.4, 21.5, and 31.5 ppm.
What is the standard deviation in ppm?

20.81 (to 4 s.f.) correct incorrect

4.311 (to 4 s.f.) correct incorrect

519.5 (to 4 s.f.) correct incorrect

19.26 (to 4 s.f.) correct incorrect

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. An experimenter suggests the null hypothesis, 'The water contains varying amounts of a strongly-coloured dye.' Which of the following could not be used to test this hypothesis?

Using a spectrometer, to assess the optical absorbance Abs correct incorrect

Using a viscometer to assess the viscosity correct incorrect

Using a titrimetric test with a complexing agent, and assessing the titres correct incorrect

Removing the water and weighing the samples correct incorrect

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. The Nernst equation is
$E_{\mathrm{O},\mathrm{R}}=E_{\mathrm{O},\mathrm{R}}^{\sout{o}}+\frac{RT}{nF}\ln \left(\frac{[O]}{[R]}\right)$.
How many degrees of freedom DF does this equation imply?

4 correct incorrect

5 correct incorrect

2.5 correct incorrect

3 correct incorrect

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. Consider the following data, which relate to amounts of a banned insecticide in food. 22.1, 22.1, 22.3, 22.4, 22.5, 23.6, 23.7, and 23.8 ppm. What is the variance of these data?

(to 4 s.f.) correct incorrect

3.55 x 10⁻¹⁵ (to 4 s.f.) correct incorrect

63.02 (to 4 s.f.) correct incorrect

0.4919 (to 4 s.f.) correct incorrect

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. When comparing the standard deviation and the variance of a data set, which of the following statements is not correct?

Variance is better than standard deviation when developing a theory. correct incorrect

Standard deviation is more useful to the chemical analyst than the variance. correct incorrect

Standard deviation is good for interpreting and reporting. correct incorrect

Modern software is good at calculating both the standard deviation and the variance. correct incorrect

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. Concerning a simple t-test: which of the following statements is NOT true?

We retain the null hypothesis if the calculated value of t is greater than t_critical. correct incorrect

The value of t depends only on the sample mean $\overline{X}$and sample size n. correct incorrect

We retain the null hypothesis if the calculated value of t is less than t_critical. correct incorrect

The value of t is a constant, so its interpretation does not depend on the chosen significance levels. correct incorrect

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. The Einstein equation is E = mc².
How many degrees of freedom DF does this equation imply?

1 correct incorrect

2 correct incorrect

3 correct incorrect

4.2 correct incorrect

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. A chemist suggests the null hypothesis, 'A reaction goes to completion.' Which alternative hypothesis allows us to reject it?

At the beginning of the reaction, we can find no product. correct incorrect

At a point exactly half-way between the start and end of the reaction, a spectroscopic technique shows the mixture contains both reactant and product. correct incorrect

The rate of reaction depends on the temperature. correct incorrect

After the reaction stops, a titration shows that the reaction mixture contains both reactant and product. correct incorrect

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. A chemist compiles a great many data sets.
Which of the following sets represents nominal data?

10, 12, 14, 16, 18, and 20 correct incorrect

First = 14.2; second = 14.4; third = 14.6; and fourth = 14.9 correct incorrect

Date, make of reagent, grid reference correct incorrect

First, second, …, fifth readings correct incorrect