1.What is the uncertainty in a measurement obtained from an electronic balance which displays a mass of 25.24 g?

ANSWER: 0.01 g

2. A Student determined the following density data for an unknown metal: 4.62 g/mL, 4.63 g/mL, 4.62 g/mL, 4.61 g/mL. Comment on the precision and the accuracy of the measurements if the true density of the metal was 6.82 g/mL.

ANSWER: Precision is good, but the accuracy is poor.

3. Consider the figure of the thermometer on the right to answer the following questions.

ANSWERS:

Record the temperature. 26.4^oC. The last digit is an estimate, therefore, 26.5^oC or 26.3^oC is also correct.
What is the uncertain digit? The last digit is uncertain.
What is the uncertainty in the measurement? 0.1 ^oC

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