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1. The results from the first
chart are likely larger values because:
A. of slight error,
uncalibrated scales, etc.
B. of damage that
was done to the scale equipment.
C. of deterioration
of the graduated cylinder.
D. of the odd miscibility
of the substances.
The best answer for this question is A. To explain why this is the best answer, let's look at the other three [incorrect] answers. Letter B is an unlikely circumstance, because no mention of equipment damage was made in the description of the experiment. We can also assume that the experiment was conducted by competent lab technicians, who would not use damaged equipment in their work. In letter C, it is impossible that a graduated cylinder would deteriorate enough to cause a significant change in observed values. As for answer D, miscibility measures the tendency of two liquids to dissolve in one another. Since the experiment involves no dissolution of compounds, miscibility is irrelevant. Answer A should be chosen, because slight experimental error is always expectable.
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2. In the second chart, which
unknown has the highest density, and what is its density?
A. Unknown A - 1.26
g/ml
B. Unknown B - 4.64
g/ml
C. Unknown C - 5.14
g/ml
D. Unknown C - 3.74
g/ml
Let's start this off by calculating
the density of each substance. By reading the description of the
experiment, we can see that we must subtract 24.5 g (the weight of the
cylinder) from the weight of each unknown. This gives us the following
data:
| Compound | Weight of compound and cylinder | ml used |
| Unknown A | 33.05 g | 45.5 ml |
| Unknown B | 21.9 g | 10.00 ml |
| Unknown C | 65.75 g | 17.56 ml |
Then, by using the formula for density (density = mass / volume), we calculate the density of each unknown. The density of A is 0.73 g/ml; B - 2.19 g/ml; C - 3.74 g/ml. It's easy to see that C has the greatest density, 3.74 g/ml, so therefore the answer is D.
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3. According to the above
information in either chart, would any of the unknowns float in water?
A. Yes - Unknown A
B. Yes - Unknown B
C. Yes - Unknown C
D. No, none of them
would float in water.
In order for a substance to float in water, its density must be less than that of water (which has a density of 1 g/ml). Looking at the densities that we calculated in the previous question, we can see that only Unknown A has the required density. Thus the correct answer is A.