AnswersTX-Chemistry AUnit Test

Unit Test — Unit test Answers

25 verified answers1 views
1
Free Preview

A scientist wants to use a model to help present the results of his detailed scientific investigation. Why would a model be useful?

A
because the model makes the concepts easier to understand
B
because the model is easy to put together and to use
C
because the model prevents other scientists from asking questions
D
because the model requires the audience to pay full attention to it
2
Free Preview

Boyd takes additional measurements of the mass of product formed in a reaction. He uses a balance that has smaller graduations than the first balance he used. What is Boyd most likely trying to change?

A
He is trying to increase his accuracy but not his precision.
B
He is trying to increase his precision but not his accuracy.
C
He is trying to decrease his precision and increase his accuracy.
D
He is trying to increase his precision and decrease his accuracy.
3

A scientist collected the following data, which show how the pressure of water vapor changes with temperature.Temperature (°C)Pressure (mm Hg)04.5109.62019.1 30 33.24058.75095.6What would a scientist do to best communicate these data to other scientists in a presentation?

A
Replace the table with text highlighting pressures.
B
Change the unit of pressure to atm.
C
Make a graph for better visual representation.
D
Display only rows 1, 3, and 6 of the data to simplify results.
4

The table shows five items that a person may consider including in a safety contract. Item numberItem1Label all containers.2Tie long hair back.3Bring a cell phone to the lab in case of emergency.4Bring a small laptop computer to the lab to use MSDS online.5Wear safety goggles at all times.Which three of the five items would be best to include in a safety contract?

A
1, 2, and 3
B
1, 2, and 5
C
2, 3, and 4
D
3, 4, and 5
5

What is one advantage of using a computer over a graphing calculator?

A
Computers are more useful for quick calculations.
B
Computers are easier to transport to remote locations.
C
Computers have lower power consumption.
D
Computers hold larger amounts of data.
6

The teacher prepares 2.50 liters (L) of a salt solution for a class experiment. How many quarts (qt) are in 2.50 L? (1 L =1.06 qt)

A
2.17 qt
B
2.36 qt
C
2.52 qt
D
2.65 qt
7

Chris is about to do an experiment to measure the density of water at several temperatures. His teacher has him prepare and sign a safety contract before beginning the experiment. Which item is most likely part of the safety contract?

A
Understand how to deal with water safely in the lab.
B
Bring an electronic copy of the MSDS on a personal laptop.
C
Do not discuss the experiment with other students in the lab.
D
Inspect the glassware for cracks or chips prior to beginning the lab.
8

How is the mode of a data set defined?

A
It is the middle value of the set.
B
It is the most common value in the set.
C
It is the average of the different values in the set.
D
It is the difference between the highest and lowest values of the set.
9

Jaime calculates the density of a slab of aluminum (Al) metal. What information does Jaime need to evaluate the accuracy of his calculation?

A
the accepted value for the density of aluminum
B
the dimensions of the slab of aluminum that he used
C
a bar graph that shows the densities of different slabs of aluminum
D
a line graph that shows how the density of aluminum varies with temperature
10

Miranda gets a small cut on her thumb after she breaks a beaker, and she begins to look around for the lab first aid kit. What important first step should she have taken?

A
She should have first called 911.
B
She should have first informed her whole class.
C
She should have first called a doctor or a nurse.
D
She should have first notified the teacher.
11

Thomas records the masses of several rocks as 7.40 g, 7.85 g, 7.60 g, and 7.40 g. What is the mode of Thomas’s data set?

A
0.45
B
7.40
C
7.55
D
7.60
12

Which is always the first step in dealing with an accident in the lab?

A
Call the emergency number, 911.
B
Call the fire department.
C
Notify the teacher.
D
Read the MSDS information.
13

Which of these steps would most likely be part of a lab procedure?

A
Write a hypothesis to answer a question.
B
Write a title at the top of a completed lab report.
C
Record the time to complete a chemical reaction.
D
Create a question on the cause of a chemical reaction.
14

Which tool was most likely used in a procedure if the lab report shows that approximately 300 mL of water was used?

A
a volumetric flask
B
a graduated cylinder
C
a pipette
D
a beaker
15

Which tool can be used to measure the volume of a liquid to one decimal place?

A
a thermometer
B
a graduated cylinder
C
an Erlenmeyer flask
D
a test tube
16

Which of these time measurements is the smallest?

A
0.02 seconds
B
0.02 teraseconds
C
2,500 milliseconds
D
25,000 nanoseconds
17

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

A
terameter
B
gigameter
C
kilometer
D
nanometer
18

A ruler has markings as shown below. Stefan uses this ruler to measure the length of a metal rod. How many decimal places should his answer include?

Question illustration
A
1
B
2
C
3
D
4
19

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.
20

Precision can be defined as the

A
exact center of a data set.
B
reproducibility of a measured value.
C
correlation between two variables that are measured in a data set.
D
agreement between a measured value and an accepted value.

Did you find these answers helpful?

More from this Course

Quiz
10 verified answers

Safety in Science

Quiz
10 verified answers

Tools, Technology, and Measurement

Quiz
9 verified answers

Scientific Methods

Unit Test — Unit test Answers — TX-Chemistry A