The value of kb of cyclohexane in the given question is; kb = 2.82 °C/m
<h3>Understanding Molality of a Solution</h3>
Molality of solution = (Number of moles of C₆H₄Cl₂)/(Mass of Cyclohexane)
Now;
Number of moles of C₆H₄Cl₂ = Mass/molar mass = 2g/147 g/mol
Number of moles of C₆H₄Cl₂ = 0.0136 mol
Molality of solution = 0.0136/(22.5 * 10⁻³ kg)
Molality of solution = 0.6 m
Now, to find kb for cyclohexane, we will use the formula;
T_b(solution) - T_b(solvent) = kb × molality of solution
Thus;
82.39 - 70 = kb * 0.6
kb = (82.39 - 70)/0.6
kb = 2.82 °C/m
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The option that best describes how the teacher likely came to this conclusion is that:
- The teacher conducted an observational study by comparing the performance on the test of those who completed their review worksheets to those who did not complete their review worksheets.
<h3>What is observational study?</h3>
An observational study is known to be a kind of study where a researcher do observes the subjects without having any form of interference with them.
Here, the researcher is said to have no control over any of the treatments that is used on the subjects. All the have to do is observe and record their findings.
See options below
A. The teacher conducted an observational study by comparing the performance on the test of those who completed their review worksheets to those who did not complete their review worksheets.
B. The teacher conducted a sample survey by asking students if they completed their review worksheets and if they think they did well on the test.
C. The teacher performed a controlled experiment in which one group of students decided not to complete their review worksheets and the other group decided to complete their review worksheets.
D. The teacher performed a random experiment in which the test scores of one group of students would be higher and the test scores of the other group would be lower.
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