Using Numbers in Measurements

​Using Numbers

Open Ended

Why is it important to distinguish between accuracy and precision in scientific measurements?

Multiple Choice

Which of the following best describes what percent error indicates in a measurement?

• How close a measurement is to the accepted value

• How consistent repeated measurements are

• The difference between two measurements

• The number of measurements taken

Multiple Choice

What is the percent error if a student determines the density of a substance to be 1.40 g/mL and the accepted value is 1.36 g/mL?

• 2.9%

• 0.4%

• 3.5%

• 4.0%

Open Ended

Explain why significant figures are important when recording measurements in scientific experiments.

Multiple Select

Select all the correct statements about counting significant figures.

• Leading zeros are not counted as significant figures.

• Trailing zeros without a decimal point are not counted as significant figures.

• All nonzero digits are always significant.

• A decimal point always makes trailing zeros significant.

Multiple Choice

Which of the following numbers has 3 significant figures?

• 402

• 0.0025

• 2,500

• 0.080

Open Ended

Describe the rule for determining the number of significant figures in the answer when adding or subtracting measurements.

Multiple Choice

Which of the following is considered an exact number and does not limit the number of significant figures in a calculation?

• The number of students in a classroom

• The result of a measurement with a ruler

• The mass of an object measured on a scale

• The volume of water in a graduated cylinder

Open Ended

Explain why only 2 significant figures are used in the final answer when dividing 15.30 g by 6.4 mL.

Multiple Choice

Which of the following numbers is correctly written in scientific notation?

• 2.4 × 10^6 μg

• 0.00256 × 10^3 kg

• 7 × 10^-5 × 10 km

• 62,000 × 10^0 mm

Multiple Select

Select all the correct steps involved in calculating with scientific notation as shown in the example: (5.44 × 10^7 g) ÷ (8.1 × 10^4 mol).

• Enter the base number using the calculator

• Use the EXP or EE button to enter the exponent

• Divide the two numbers as usual

• Ignore significant figures in the final answer

Open Ended

Describe the difference between direct and inverse proportion, and provide an example of each.

Multiple Choice

Which of the following best describes the difference between accuracy and precision?

• Accuracy is how close a measurement is to the accepted value, while precision is how close repeated measurements are to each other.

• Accuracy is how close repeated measurements are to each other, while precision is how close a measurement is to the accepted value.

• Accuracy and precision both mean how close a measurement is to the accepted value.

• Accuracy and precision both mean how close repeated measurements are to each other.

Open Ended

How does percent error help in evaluating the accuracy of a measurement?