Chapter 2-Measurements and Numbers

What is the magnitude of uncertainty in the measured value 0.02090?

±0.00001

What is the magnitude of uncertainty in the measured value 30,000.500?

±0.001

What is the uncertainty in the number 4.470 x 10 ? ±0.001, or ±0.001 x 10ˆ2, or ±0.01, or ±0.1, or ±0.01 x 10ˆ2.

±0.001 x 10ˆ2 and ±0.1

What is the magnitude of uncertainty in the measured value 37.50?

±0.01

What is the error in the measured quantity 105.43 meters? Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. ±5 meters, or ±0.43 meters, or ±0.430 meters, or ±0.4 meters, or ±0.03 meters, or ±0.01 meters, or ±0.001 meters

±0.01 meters

What is the error in the measured quantity 25.6 mL? ±1 mL, or ±0.1 mL, or ±0.6 mL, or ±5.6 mL, or ±6 mL

±0.1 mL

What is the error in the measured quantity 75 degrees? Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. ±5 degree, or ±1 degree, or ±0.1 degree, or ±0.05 degree, or ±0.01 degree.

±1 degree

What is the magnitude of uncertainty in the measured value 4o,5õo?

±10

What is the magnitude of uncertainty in the measured value 550,000,000?

±10,000,000

What is the error or magnitude of uncertainty (±) in the distance to the moon presented (234,000 miles)?

±1000 miles

The process of removing the non-significant digits in a calculated number to reflect the uncertainty in the measured values used in the calculation is called .................................... .

rounding

Express 4 in multiples of the base number.

(1/4•1/4•1/4)

How close a result is to its true value is a measure of ........... .

accuracy

How many significant figures are in one dozen?

infinite

What is the magnitude of uncertainty in a ½ dozen?

none

For a temperature measured to 75.43 degrees, what would be the smallest calibration marks on the thermometer used to make this measurement?

tenths of a degree

How many significant figures are in the measured value 37.50?

4 significant figures

How many significant figures are in the measured value 4o,5õo?

4 significant figures

How many significant figures are in the measured value 0.30574?

5 significant figures

What types of numbers are considered exact or without error in the presented value? (small) counted numbers, or simple fractions, or measured numbers, or defined numbers.

(small) counted numbers, simple fractions, and defined numbers

0.0038965 rounded to four significant figures becomes ....................... .

0.003897

When converting 2.470 x 10 to decimal notation, how many significant zeros and how many non-significant zeros will the decimal number have? no significant zero, or 1 significant zero, or 2 significant zeros, or no non-significant zero, or 1 non-significant zero, or 2 non-significant zeros.

1 significant zero and 2 non-significant zeros

95,000 rounded off to one significant figure becomes .............. .

100,000

145,789 rounded off to three significant figures becomes ....................... .

146,000

172.540 rounded off to two significant figures becomes ...................... .

170

188,501 rounded to three significant figures becomes ........................... .

189,000

Consider the problem (3.7 x 10) x (2.45 x 10) = How many significant figures will the coefficient of the answer have?

2

How many significant figures are in the measured value 550,000,000?

2 significant figures

Consider the mathematical expression 4. What is the base number?

4

How many significant figures should be retained in the decimal equivalent of 3.030 x 10ˆ4?

4

How many significant figures are in the measured value 0.02090?

4 significant figures

Consider the mathematical expression 4. What is the exponent?

7

How many significant figures are in the measured value 30,000.500?

8 significant figures

What is the final step of an addition or subtraction involving scientific notation numbers? Write down the number from the calculator display., or Check if the coefficient has the decimal in the correct location - make adjustments if necessary.

Check if the coefficient has the decimal in the correct location - make adjustments if necessary.

What do you have to do before adding or subtracting scientific notation numbers? Match the power of ten for all numbers., or Make sure all numbers are expressed in proper scientific notation., or Make sure all numbers have been converted from decimal to scientific notation., or No need to worry-the calculator will figure this out.

Match the power of ten for all numbers; Make sure all numbers have been converted from decimal to scientific notation

In terms of magnitude, is 1.25 x 10ˆ7 a big or a small number?

big; 12,500,000

Uncertainty in measurements is associated with the concepts of ........... and ............ . .

accuracy; precision

Consider the problem (3.7 x 10) x (2.45 x 10) = Do you have to add or subtract the exponents?

add

Which depends on the physical measuring device used to make the measurement? Accuracy, or Precision, or both accuracy and precision.

both accuracy and precision

Which depends on the skill of the person performing the measurement? Accuracy, or Precision, or both accuracy and precision.

both accuracy and precision

Consider the following task: Determine the gas mileage of two cars. To complete the task you need to decide which parameters affect gas mileage. Let's assume that you came up with these factors: car type and size of engine, car age, driving habits, weather conditions, traffic conditions, tire inflation. Which of the factors would cause respectively random and systematic errors in your determination of gas mileage? car type ---> engine size ---> age of car ---> driving habits ---> weather conditions ---> traffic conditions ---> tire inflation --->

car type ---> systematic errors engine size ---> systematic errors age of car ---> systematic errors driving habits ---> random errors weather conditions ---> random errors traffic conditions ---> random errors tire inflation ---> systematic errors

How does a chemist control or minimize random errors?

control the environment and recalculate to remove errors in data

What types of numbers are considered exact or without error in the presented value? counted numbers (regardless of their magnitude), or counted numbers (but only below a reasonable limit and under controlled conditions), or simple fractions, or defined numbers.

counted numbers (but only below a reasonable limit and under controlled conditions), simple fractions, and defined numbers.

Chemistry is an experimental science; that is, chemical discoveries are made as a result of ......................... .

experimentation

Consider the following statement:"The number 3.746 rounded off to two significant figures can first be rounded to 3.75, and then to 3.8." True or False.

false

Consider the statement:''All counted numbers are considered exact.'' True or False.

false

Consider the statement:''There are 4,555 people in the stadium attending the soccer match.'' In this statement, the number 4,555 is an exact number. True or False.

false

Consider this statement:''Qualitative observations use numbers.'' True or False.

false

To determine how many significant figures should be recorded in a product or quotient, the answer must have the same uncertainty as the term with the largest uncertainty. True or False.

false

To determine how many significant figures should be reported in a sum or difference, the total of significant figures in each term is counted. The result will have the same number of significant figures as term with the fewest significant figures. True or False.

false

When comparing two instruments, the more precise instrument will always be the more accurate one. True or False.

false

Consider this statement:'''An oral dose of 5 cc. is a qualitative measurement'' True or False.

false, it is a quantitative measurement

Consider the statement:''A machinist determines the length of an aluminum rod to be 5 inches.'' In this statement, is the number 5 an exact number or an inexact number?

inexact number

In calculations involving both exact and inexact numbers, which numbers will be used to determine the significant figures in the answer? exact numbers, inexact numbers, or both exact numbers and inexact numbers.

inexact numbers

How many significant figures are in ¼ dozen?

infinite

Consider this statement:"When computing a result with measured numbers on a calculator, all the digits displayed by the calculator are significant." True, or False, or it depends - they may or may not be.

it depends - they may or may not be

When converting 1.09 x 10ˆ-5 to a decimal number, will the decimal point be moved to the right or to the left?

left

Medications with a narrow therapeutic index are those that cause adverse affects when administered in very small amounts above what is considered an effective dose. In other words there is a small difference between an effective dose and a toxic dose.When administering a medication that falls into this category, is it okay for a physician or nurse to give a patient an injection with a syringe graduated in whole mL units, if the medication shows signs of adverse affects at +0.05 mL? yes or no.

no

Is 23.45 x 10ˆ3 expressed in proper scientific notation? yes or no.

no, the coefficient value must be between 1 and 10

How many digits in a measurement are estimated?

one

How close to each other multiple measured results obtained in the same fashion are to each other is a measure of ........... .

precision

To completely describe a substance, one or more .............................. measurements must be taken.

quantitative

What type(s) of error(s) is/are associated with measurements? random errors, or systematic errors, or random and systematic errors.

random and systematic errors

A .......... or .......... is used to control for instrument problems.

reference; standard material

In order to simplify the writing of either very large or very small numbers, scientists use ......................... ........................... .

scientific notation

Scientists use a specific format to express large or small numbers. What is the notation called?

scientific notation

A digit that is either reliably known or estimated is a ..................... ........................ .

significant figure

Consider the statement:''If you have 1/2 dollar you have exactly 50 cents.'' True or False.

true

Consider the statement:''The uncertainty (error estimate) of a measured value is always presented in the last recorded significant digit.'' True or False.

true

Consider the statement:''There are 100 cents in one dollar.'' In this statement, the number 100 is an exact number. True or False.

true

Consider this statement:"Mathematical operations should neither increase nor decrease the uncertainty of experimental measurements." True or False.

true

Consider this statement:''Measurements are used by chemists to better understand matter.'' True or False.

true

Consider this statement:''Quantitative and qualitative observations are both used to describe the physical properties of matter'' True or False.

true

What are the two types of information conveyed when a measured value is recorded? size or magnitude, or the behavior of matter, or uncertainty/error, or the physical state.

uncertainty/error

Is the notation 1 x 10 the same as 10? yes or no.

yes