AnswersTX-Chemistry AUnit Test

Unit Test — Unit test Answers

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21
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A scientist would most likely need to update her model when it

A
has become too simple.
B
no longer supports the latest results.
C
reduces the need for verbal explanation of data.
D
no longer appears interesting.
22
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What must be part of a quantitative observation?

A
a change of state
B
a change in size
C
a number
D
a color
23

Error bars on four different data points are shown below.Which of these data points is the most reliable?

Question illustration
A
point 1
B
point 2
C
point 3
D
point 4
24

The actual density of iron is 7.874 g/mL. In a laboratory investigation, Jason finds the density of a piece of iron to be 7.921 g/mL. What is the percent error that is associated with Jason’s measurement?

A
-4.7%
B
-0.6%
C
0.6%
D
4.7%
25

How can one determine the median of a data set?

A
by ordering the data points and finding the middle value of the set
B
by ordering the data points and finding the most common value in the set
C
by finding the average of the different values in the set
D
by finding the difference between the highest and lowest values of the set
26

Emily spills concentrated sodium hydroxide solution on her lab bench. What she should do first?

A
Notify her teacher.
B
Clean up the spill herself.
C
Clean up the spill with her classmates.
D
Read the MSDS for sodium hydroxide.
27

A tree farm sells trees based on height in increments of 10 feet. Which graph would best show the current stock of trees?

A
bar graph
B
line graph
C
histogram
D
scatterplot
28

Which of these units is most appropriate for describing a 26-mile marathon run?

A
terameter
B
gigameter
C
kilometer
D
nanometer
29

The MSDS for benzene indicates that it is a clear liquid that has a substantial vapor pressure. It has a health rating of 2, a fire rating of 3, and a reactivity rating of 0. It is a cancer-causing agent. Based on this information, which statement about benzene is accurate?

A
Benzene readily reacts with moist air.
B
Benzene explodes if the container is shaken.
C
Benzene must be kept away from flames.
D
Benzene must be stored under high pressure.
30

Zachary, a lab instructor, is writing a safety contract that his chemistry class will use for an experiment. He mentions that students should not eat or drink in the lab. Which other item should also be included?

A
Do not wear hats in the lab.
B
Do not bring backpacks to the lab.
C
Do not open any windows in the lab.
D
Do not chew gum in the lab.
31

Ben will be conducting an experiment in which he reacts metals with different concentrations of acid in test tubes. What should Ben wear to best protect himself during the experiment?

A
heat-proof gloves, a lab coat, and close-toed shoes
B
a lab coat, chemical gloves, and close-toed shoes
C
goggles, a lab coat, and heat-proof gloves
D
goggles, a lab coat, chemical gloves, and close-toed shoes
32

Read the lab procedure for a controlled experiment that looks at the effect of heat on the circumference of bicycle tires.Step 1: Pump up six identical bike tires to the recommended air pressure.Step 2: Place three tires under heat lamps, and keep the other three tires at room temperature.Step 3: After four hours, measure the circumference of each tire. Step 4: Record your results in the table.Step 5: (?)Which step should be next in this procedure?

A
List the materials that are needed.
B
Write a conclusion for the experiment.
C
Write a hypothesis for the results.
D
Draw a table for the observations.
33

What emotional state is important to maintain while reporting an accident in the lab?

A
fear
B
anxiety
C
calmness
D
embarrassment
34

A researcher wants to show the effects of slight changes in pH on the reproductive rates of fish in a lake. Why would a table be more suitable than a graph to show the data?

A
Tables better illustrate precise data points.
B
Tables have data points with more significant figures.
C
Tables better illustrate the comparison of two different data sets.
D
Tables are better suited for displaying real-world data.
35

During a conference presentation, a scientist described the materials that she used and how she performed her experiments. Which best explains why a scientist would share these details in a conference?

A
It tells the audience if the results support or contradict the hypothesis.
B
It tells the peers if the study is supported by mathematical models.
C
It informs the peers if the results are supported by other scientists.
D
It informs the audience if the study included controlled tests.

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