Question 1

Which of the following best describes a random error in a laboratory experiment?

Accepted Answer

An unpredictable fluctuation in measurements that can be either too high or too low.

Question 2

A student measures the mass of a sample three times and gets values that are all higher than the accepted value. What type of error is most likely present?

Accepted Answer

Systematic error

Question 3

Which of the following actions would most likely reduce random error in an experiment?

Accepted Answer

Taking multiple measurements and averaging the results.

Question 4

Given the formula $\%\ 	ext{error} = \frac{\left| 	ext{Experimental value} - 	ext{Theoretical value} ight|}{	ext{Theoretical value}} 	imes 100$, what is the percent error if the experimental value is 24.8 and the theoretical value is 25.0?

Accepted Answer

$0.4\%$

Question 5

Which of the following is an example of a systematic error when weighing a sample?

Accepted Answer

The balance is not zeroed before use.

Question 6

If a student consistently records a mass that is 0.2 g higher than the true value due to a calibration issue, what type of error is this?

Accepted Answer

Systematic error

Question 7

A student calculates a percent error of $12\%$ for an experiment. According to standard laboratory guidelines, is this error generally considered acceptable?

Accepted Answer

No, because errors above $10\%$ are usually not acceptable.

Question 8

Which of the following would NOT be considered a source of random error?

Accepted Answer

A balance that is always off by 0.1 g.

Question 9

A student weighs a sample before all the water has evaporated. What type of error does this represent?

Accepted Answer

Systematic error

Question 10

Which of the following best describes the theoretical value in the percent error formula?

Accepted Answer

The value calculated from accepted scientific data.

Question 11

If a student records the wrong mass of an anhydrous object due to a misreading, what type of error is this?

Accepted Answer

Gross error

Question 12

Which of the following would most likely help to identify and correct a systematic error?

Accepted Answer

Calibrating the measuring instrument before use.

Question 13

A student finds that their measured values are always lower than the theoretical value. Which of the following is the most likely explanation?

Accepted Answer

There is a systematic error causing a consistent bias.

Question 14

Which of the following scenarios would most likely introduce a random error in a mass measurement?

Accepted Answer

A sudden draft of air affects the balance reading.

Question 15

If the experimental value is 50.0 and the theoretical value is 52.0, what is the percent error?

Accepted Answer

$4.0\%$

Question 16

Which of the following is the best way to minimize random errors in a set of measurements?

Accepted Answer

Take multiple measurements and use the average.

Question 17

A student uses the wrong formula to calculate percent error. What type of error does this represent?

Accepted Answer

Calculation error

Question 18

Which of the following is NOT a feature of random errors?

Accepted Answer

They always cause results to be too high.

Question 19

A student finds that their percent error is negative. What does this indicate about their experimental value?

Accepted Answer

The experimental value is lower than the theoretical value.

Question 20

Which of the following best describes the purpose of calculating percent error in an experiment?

Accepted Answer

To compare the experimental value to the accepted theoretical value and assess accuracy.

Understanding Error in Chemical Measurements: Random and Systematic Errors

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