Chem Day 3

The number 0.025349 rounded correctly to three significant figures is ______.

0.0253

A mass is recorded as 15.02 g. Given the accepted level of uncertainty in any recorded measurement, select the range in which this mass will fall.

15.01 - 15.03 g

Which of the following statements correctly describe how to round the number 32.6721 according to the number of significant digits in each case? Select all that apply.

32.67 to four significant figures 33 to two significant figures 30 to one significant figure

Which option(s) correctly describes the procedure used to determine the number of significant digits in a reported quantity?

All digits from the first nonzero digit onward (going to the right) are significant if there is a decimal point. If there is no decimal point, we assume that the trailing zeros are not significant unless exponential notation clarifies the quantity. Start at the left and move right until you reach the first nonzero digit.

A student carried out an experiment using a circular piece of aluminum foil (of known thickness) to determine the value of π. The accepted value of π is 3.1416. The student's results were 3.6689, 3.6691, 3.6687, and 3.6693. Select the best statement about this student's results in regard to precision and accuracy.

High precision and low accuracy

Which of the following statements describe how to round a number correctly, using the conventions followed by this text?

If the digit removed is a 5 followed only by zeros, the preceding number is increased by 1 if it is odd. If the digit removed is greater than 5, the preceding number increases by 1. Rounding at each intermediate step of a multistep calculation can introduce additional error.

Which of the following statements correctly describe accuracy and precision? Select all that apply.

Precision is the term used to refer to how close two measurements are to each other. Accuracy is the term used to compare an experimental result to the "true" or accepted value.

Rule For Rounding Which of the following statements correctly reflect the rule governing rounding in a calculation?

The least certain measurement determines the certainty of the answer. Rounding is necessary when there are too many digits after a calculation.

A nail is measured with a ruler and its length is reported as 5.46 cm. Select all the statements that are correct about the certainty and uncertainty represented in this recorded measurement.

The uncertainty is in the final digit of the measurement. The uncertainty can be expressed by reporting the measurement as 5.46 ± 0.01 cm.

Which option correctly describes the significance of zeros in a reported number? 2

Zeros to the right of the number are significant as long as there is a decimal point present. Zeros to the left of the first nonzero digit are not significant.

When adding or subtracting quantities, the answer is rounded so that it has the same number of ______ in the quantity that has the fewest of these. When multiplying or dividing, the answer is rounded to contain the same number of ______ in the quantity that has the fewest of these.

digits after the decimal; significant figures

The measurement with the___________amount of certainty in a calculation sets the limit for the entire calculation and determines the number of _____________figures in the final answer.

least, significant