Chemistry A
Which option shows a ratio that could be used to correctly convert 10 tons into kilograms?(Select all that apply)
0.45 kg/1 lb 2,000 lbs/1 ton
Which options show ratios that could be used to correctly convert 5.2 m/s to km/h(Select all that apply)
1 km/1,000 m 1 hr/3,600 s
Which option shows the correct setup for converting 15 days to seconds?
15 days⋅24 hr/1day⋅60 min/1 h⋅60 s/1 min
When an atom of calcium (Ca) forms a cation by losing two electrons, what is the ion's charge?
2+
When an atom of oxygen (O) forms an anion by gaining two electrons, what is the anion's charge?
2−
Examine the unit pairs in the following list. 1. kg and m 2. s and g 3. m and m2 4. s and m/s Which option correctly identifies the list numbers that contain a base unit and a derived unit?
3 and 4
Examine the scenario. The mass of a sample was measured to be 12.00 g, and its volume was determined to be 4.0 mL. What is the sample's density if the formula for density is mass divided by volume (mass÷volume)?(mass÷volume)? Note: Make sure your answer includes the correct number of significant figures.
3.0 g/mL
If one beam measures 1.5 x 10^3 m, what is the total length for two beams?
3.0 x 10^3 m
Which option provides numbers written correctly in scientific notation?
4.0 x 10^5
Examine the table. Isotope Atomic Mass Abundance 63Cu 62.930 69.15% 65Cu 64.928 30.85% Based on the information provided for the isotopes of copper (Cu), what is the average atomic mass of copper?
63.55 amu
Examine the table containing information about beryllium (Be). Number of Protons Number of Neutrons Number of Electrons 4 5 4 What is a beryllium atom's atomic mass?
9
What is a mixture?
A mixture is a combination of two or more pure substances that can be physically separated.
Read the excerpt and study the data table. A group conducted three trials to measure the mass of a sample of steel. The results are given in the table below. Measurements of Steel Sample TrialMass1185.54 g2185.57 g3185.52 g What can be inferred about the group's data if the known mass of the sample was 185.04 g?
A systematic error occurred, causing the data to read 0.50 g higher for each trial because the balance was improperly tared.
Which options make true statements about absolute error?(Select all that apply)
Absolute error is determined by subtracting the experimental value from the accepted value. Absolute error has the same units as the measurement.
Examine the following isotopes of silicon (Si). silicon-28 (28Si)silicon-29 (29Si)silicon-30 (30Si) How can the periodic table be used to identify which isotope of silicon is most abundant in nature? Hint: Look at your periodic table. If you require the use of a text reader, select the long description to receive the information.
According to the periodic table, silicon's weighted average atomic mass is 28.09. Since it is so close to the mass number of silicon-28, it can be concluded that silicon-28 is the most abundant isotope.
Which statements correctly describe how elements and pure substances relate?(Select all that apply)
All elements contain atoms of a single type, but not all pure substances contain a single type of atom. All elements are pure substances, but not all pure substances are elements.
What is a common feature among the burette, pipette, and graduated cylinder?
All of the instruments can be used to measure the volume of a liquid.
Examine the statement. An ore is a rock that is mined from the earth's surface and physically processed to obtain specific elements of the periodic table. Which option correctly classifies the type of matter that ore belongs to and provides an accurate explanation for the classification?
An ore is a heterogeneous mixture because it can be physically separated and is made up of more than one pure substance.
How did Dmitri Mendeleev's periodic table lead to a better understanding of elements?(Select all that apply)
By ordering elements according to atomic weight, Mendeleev was able to predict certain characteristics of various elements. By ordering elements according to atomic weight, Mendeleev was able to show trends that correlated elements' weight with their chemical and physical properties.
Based on electrostatic forces, how would two electrons interact with each other?
The electrons would repel each other because they have the same charge.
Examine the table. Physical Properties Substance/Object Density(g/cm3) Ethyl Alcohol (C2H6O) 0.79 Hexane(C6H14) 0.66 Water(H2O) 0.997 Based on the physical properties of ethyl alcohol, hexane, and water shown in the table, which method should be used to separate a mixture of these substances, and why?
Centrifugation should be used because it separates substances based on density and all three substances have different densities.
Examine the statement about alchemy. Alchemy used minerals, herbs, and plants to treat sick patients and extend life. Based on the statement, which option demonstrates how chemistry is similar to alchemy?
Chemistry has led to the discovery of radioactive substances, which have been used in imaging tests that screen for disease.
Which option correctly summarizes the use of chemistry in modern society?
Chemistry is an interdisciplinary science that can be used in other areas of science, like engineering, sports medicine, and cooking.
Which option correctly defines chemistry?
Chemistry is the study of matter and the changes it undergoes.
Which option correctly describes how chemists differ from alchemists?
Chemists openly collaborate and publish findings to further the advancement of society, while alchemists wrote in code to keep their work secret.
Why was Marie Curie's discovery of and research regarding radium (Ra) important to chemistry?(Select all that apply)
Curie's Radium Institute conducted research on the biological and medical effects of radioactivity. The study and use of radium became a starting point for medical tests and the treatment of cancer.
Which option correctly explains whether density is an intensive or extensive physical property?
Density is considered an intensive property of matter because it does not depend on the amount of matter. As the mass of a substance increases, the volume will also increase proportionately.
Read the scenario. A mixture contains ethanol (C2H6O) and water (H2O). The boiling point of ethanol is 78.24 °C, and the boiling point of water is 100 °C. Based on the physical properties of water and ethanol, which method should be used to separate them, and why?
Distillation should be used because it separates substances based on boiling point and both substances have different boiling points.
When should a scientist use distillation instead of crystallization to separate a salt water mixture?
Distillation should be used to separate a saltwater mixture if the scientist intends to recover both the water and salt.
How did the Dalton's model of the atom falsely represent atomic structure?
It showed that atoms are tiny, indivisible spheres with no charge and no substructure.
How is filtration used to separate a heterogeneous mixture?
Filtration is used to separate a heterogeneous mixture by using the physical property of particle size.
Considering the definition of a pure substance, which options correctly explain why a substance could be classified as being a pure substance?(Select all that apply)
Gold (Au) is a pure substance because it is an element. Ammonia (NH3) is a pure substance because it is a compound formed between nitrogen (N) and hydrogen (H). Air is a pure substance because different gases and particles are mixed together.
Read the scenario and study the data table. Two different groups conducted an experiment to determine the density of aluminum (Al) using multiple trials. The results are given in the following data table. Density Results for Aluminum TrailGroupGroup 212.8 g/mL2.75 g/mL22.6 g/mL2.80 g/mL32.7 g/mL2.74 g/mL Since the known density of aluminum is 2.70 g/mL, which options most accurately explain the probable source of error for a group?(Select all that apply)
Group 1's measurements were affected by random error from an experimenter. This is indicated by how the measurements were both higher and lower than the accepted value. Group 2's measurements were affected by systematic error from an instrument. This is indicated by how the values were consistently higher than the accepted value.
Read the statement. The element phosphorus (P) was discovered by alchemist Hennig Brand when he tried to separate the substances in urine and isolate gold (Au). Which option correctly explains how Hennig Brand's work in alchemy affected chemistry?
Hennig Brand's use of boiling to manipulate matter was related to the development of more refined methods for separating substances in chemistry, like distillation.
Which statements correctly identify a type of mixture?(Select all that apply)
Heterogeneous mixtures have parts that are distributed unevenly. Homogeneous mixtures have parts that are distributed evenly.
Considering the description of how a compound is related to a pure substance, which options correctly explain why a substance could be classified as being a pure substance?(Select all that apply)
Iron (Fe) is a pure substance because it is an element. Methane (CH4) is a pure substance because it is a compound formed between carbon (C) and hydrogen (H).
Study the image of laboratory equipment. © 2016 FlipSwitch Which option accurately describes the purpose of the piece of lab equipment shown?
It allows experimenters to move test tubes without touching them with their hands.
Read the scenario. An experimenter is interacting with liquid chlorine (Cl). She is wearing thick rubber gloves, a lab apron, and goggles. Which option correctly infers the hazards of chlorine that the experimenter must be avoiding?
Liquid chlorine is known to cause severe skin burns and serious eye damage.
Which chemist discovered human-made CFCs interacting with ozone molecules in the atmosphere and then played an important role in convincing lawmakers to permanently ban CFCs?
Mario Molina
Which option correctly describes melting point and explains why it is as physical property?
Melting point is the temperature at which a substance changes from the solid to liquid state. It is a physical property because measuring melting point changes the identity of a substance.
Which statements accurately describe how the electrostatic forces of protons and electrons work within an atom?(Select all that apply.)
Particles with the same charge repel each other. Particles with opposite charges are attracted to each other.
Which options make true statements about relative error?(Select all that apply)
Relative error is determined by subtracting the measured value from the accepted value and then dividing by the accepted value. Relative error is a ratio and has no unit of measurement with the number.
Study the image of two rulers measuring an object. © 2016 FlipSwitch Which of the rulers is more accurate, and why?
Ruler A is more accurate because it has a higher level of certainty. The ruler has more divisions, so a larger number of significant figures can be determined.
How did Ernest Rutherford's atomic model compare to the plum-pudding model?
Rutherford's atomic model was the first to show that the positive charges within an atom are not uniformly distributed, as shown in the plum-pudding model, instead, they are located in a central nucleus.
Which option correctly describes how chemistry has benefited human health?(Select all that apply)
The discovery of radioactive substances has led to the development of imaging tests that screen for disease. The use of chemical substances to enhance soil fertility has led to the development of higher crop yields and more food.
Examine the statement. After the Civil War, many farmers in the South were poor and had little money. Based on the statement excerpt, how did the farmers' economic status encourage the collaboration and discoveries made among scientists in the fields of chemistry, agriculture, and industry? (Select all that apply.)
Scientists from different fields researched peanuts and educated farmers on peanuts' ability to enrich soil and provide a cheap, convenient source of protein for lower-income people. Scientists from different fields worked toward creating efficient commercial and industrial products from common crops and spreading proper agriculture techniques to people who could not attend school.
Why should scientists always wash their hands after conducting an experiment and never eat food in a laboratory?(Select all that apply)
Several chemicals are known to be toxic if ingested, and some cause skin irritations. Many chemicals can react with other substances or materials they interact with, such as food. Several chemicals are known to cause irritation to the eyes if touched with contaminated hands.
Which options contain true statements about significant figures?(Select all that apply)
Significant figures are the digits in a measured value that represent the accuracy of the measurement. Significant figures reflect the accuracy of the instrument. Significant figures are the digits that can be read from the instrument along with an individual's estimated digit.
How is atomic mass measured?
Since the atomic mass is calculated as the sum of protons and neutrons, it is measured in amu. This is because protons and neutrons each have a mass of 1 amu.
Read the excerpt from NASA about its history. A Brief History of NASA Congress and the President of the United States created the National Aeronautics and Space Administration (NASA) on October 1, 1958. NASA's birth was directly related to the pressures of national defense. After World War II, the United States and the Soviet Union were engaged in the Cold War, a broad contest over the ideologies and allegiances of the nonaligned nations. During this period, space exploration emerged as a major area of contest and became known as the space race. Garber, Steve, and Roger Launius. "A Brief History of NASA." NASA. National Aeronautics and Space Administration, 2005. Web. Based on the excerpt, what logical argument can be made about the Cold War and advancements in science? (Select all that apply)
The Cold War directly led to a government-funded organization that studied nuclear chemistry in order to fuel space expeditions. The Cold War directly led to the United States' movement toward a better understanding of the importance of science in education. The Cold War directly led to a government-funded organization that studied nuclear fission in order to create atomic bombs. The Cold War directly led to the United States' involvement in the space race with the Soviet Union.
Which options make a true statement about base units in the SI system?(Select all that apply)
The base units in the SI system are independent of any other unit. There are seven fundamental units in the SI system.
Examine the scenario and study the image. Four scientists are performing an experiment with a chemical substance they have never worked with before. Within the laboratory, they see the following safety symbol above a bottle containing the chemical. © 2016 FlipSwitch What does this symbol imply about the chemical within the container?
The chemical inside the container is harmful to people's eyes.
Which statement most accurately describes an extensive physical property for a coin?
The coin has a mass of 6.25 g.
What does it mean if a group records the same mass of an object each time it is measured?
The data is precise.
How could a systematic error be avoided when using an electronic balance for an experiment?
The experimenter should always properly tare the balance before measuring the mass.
Examine the image of the laboratory equipment. © 2016 FlipSwitch Which option accurately describes the purpose for the pieces of lab equipment shown?
The graduated cylinders are used to measure the volume of liquids.
Examine the image and read the scenario. Used by permission of Cunningham Pastured Meats. Glass jars contain fresh, unpasteurized milk. The jars are placed on a kitchen counter. Over time, the cream rises to the top of the jars and the milk sinks to the bottom. Which answer correctly explains the method that should be used to separate the mixture of milk and cream?
The mixture should be skimmed. A ladle should be used to collect and transfer the lower-density cream to another container.
What piece of lab equipment would help a scientist get the most precise and accurate results when measuring the width of a textbook?
The ruler would be the most precise because it has markings that represent smaller values.
Read the scenario. The label on a bottle of reduced-fat salad dressing includes the following statement: "Shake well." Which option correctly explains why the salad dressing is labeled with this statement?
The salad dressing is a heterogeneous mixture, so it separates and must be shaken to disperse the ingredients evenly.
Which option accurately describes the technique a scientist could use to mix two liquids and then heat the mixture?
The scientist could pour the two liquids into a beaker, mix them with a stirring rod, lift the beaker with beaker tongs, and place the beaker in a ring stand's ring clamp over a Bunsen burner.
Examine the list of scientists. Marie Curie Michael Faraday George Washington Carver Ahmed Zewail What do the scientists have in common? (Select all that apply)
The scientists made significant advances in chemistry. The scientists overcame personal difficulties prior to achieving their success.
Examine the scenario. To separate ethyl alcohol from a mixture, a group of scientists need to boil the mixture until it reaches 78.24 °C or 172.83 °F. The scientists boil the mixture and collect the gases that evaporate. When the scientists analyze the gases that evaporated from the mixture, they find that the gases contain no ethyl alcohol. The scientists refer back to their lab notes and realize that the final temperature of the mixture was 78.24 °F. Which option logically explains why there was no ethyl alcohol in the gases that the scientists collected?
The scientists measured the temperature with the wrong units, so the reaction mixture overheated, and all the ethyl alcohol evaporated.
Read the scenario. Three scientists measure the mass of three substances using an electronic balance. They then compare their measurements to the accepted value of each substance and discover that each of their measurements is much higher than the accepted value. Which option most accurately describes what the scientists should do to correct this error and make the correct measurements?
The scientists should check their balance and make sure it gets calibrated correctly or repaired.
Read the scenario. A group of scientists use a graduated cylinder to measure the volume of a liquid. Which options accurately describe what the scientists should do to reduce the chance of random error affecting their measurement?(Select all that apply)
The scientists should ensure they measure the liquid using the bottom of the meniscus any time they make a measurement. The scientists should measure the liquid multiple times and then calculate the average of all the measurements.
Examine the scenario. A student describes a mixture by writing, "It is a colorless liquid with white particles dispersed throughout the liquid. Some white particles have settled on the bottom of the test tube." What type of mixture is the student is describing, and why?
The student is observing a heterogeneous mixture because the mixture is not the same throughout.
Study the data table showing the mass of a cylinder measured multiple times. TrailMass of Cylinder115.20 g215.25 g315.15 gAverage15.20 g If the accepted mass value of the cylinder is 15.10 g, which options correctly explain the error types of the experiment?(Select all that apply)
The systematic error can be reduced by averaging the three trials of mass. Multiple trials were conducted and averaged in order to minimize the effect of random error in the measurements.
When using a graduated cylinder to measure volume, what is the proper technique(Select all that apply)
The volume should be read at the bottom of the meniscus. The graduated cylinder should be on a flat surface.
Which statements accurately describe an intensive physical property for a 100 mL sample of pure water (H2O)?(Select all that apply)
The water sample is in the liquid state. The water sample's density is 0.998 g/mL.
Examine the scenario. A group of scientists observe the physical properties of a substance. How do the scientists identify which properties of the substance are the physical properties?
They identify the substance's properties that do not alter the substance's identity.
Which statement accurately describes how J.J. Thomson's model of the atom differed from John Dalton's model of the atom?
Thomson's model depicted atoms as tiny positive spheres with negative charges while Dalton's model showed atoms as spheres with no charge.
Which option correctly describes how modern chemistry has been used to decrease health issues in society?(Select all that apply)
Through the process of blood analysis, doctors can prescreen genetic abnormalities. Through chemical analysis, vaccinations have been created to reduce the spreading of diseases. Through the process of radiation, many bacteria on fresh produce have been destroyed.
Read the scenario and list of properties. A jar contains a mixture of water (H2O), iron (Fe) filings, and aluminum (Al) washers. The properties of the items in the mixture are as follows: Water is a clear fluid that has a boiling point of 100 °C. Iron filings are small, irregularly shaped magnetic pieces of metal. Aluminum washers are flat, circular non-magnetic pieces of metal. Based on the items' properties, which option describes the most effective method for separating the items from one another?
Use a filter to separate the water from the iron filings and aluminum washers. Then, use a strong magnet to separate the iron filings from the aluminum washers.
Read the statement. Iodine (I) crystals are not soluble in water (H2O), but salt (NaCl) crystals are soluble in water. Which option describes the most effective method for separating a mixture of water, salt crystals, and iodine crystals?
Use filter paper to trap the insoluble iodine crystals, allowing the salt water solution to go through the filter paper. Then, allow the water to evaporate, leaving the salt behind.
Which options correctly describe the alchemist Paracelsus's beliefs about using minerals instead of traditional medicine to treat diseases?(Select all that apply)
Which options correctly describe the alchemist Paracelsus's beliefs about using minerals instead of traditional medicine to treat diseases?(Select all that apply) Paracelsus felt that the mind played a major role in healing the body, and, since society no longer believed in traditional medicine, he utilized a different form of healing that used minerals. Paracelsus disagreed with traditional medicine because he felt that the body must be in harmony with nature and the minerals from nature could be used to bring the body into balance.
Why was the work of Ahmed Zewail important to chemistry?
Zewail developed a laser technique that enabled the study of atoms' behavior during chemical reactions.
What is an atom?
a substance that cannot be changed into a simpler substance under normal laboratory conditions
Examine the scenario and table. A mixture of propylene glycol, ethyl alcohol, acetone, and water (H2O) is distilled. A group of scientists want to isolate each substance, so they plan to distill the mixture and collect each of the first three substances that boil off in separate containers. Before they start, they examine the table of each substance's boiling point below. Substance Boiling Point (°C) Propylene Glycol 187.3 Ethyl Alcohol 78.5 Acetone 56.08 Water 99.97 Which answer correctly shows the order the first three substances will boil off of the mixture and be collected by the scientists?
acetone, ethyl alcohol, water
Read the incomplete statement. The mass of a sample is determined using a __________, and the volume of a sample is determined using a __________. Which answers correctly complete the statement? (Select all that apply.)
balance; burette balance; graduated cylinder
Which options list an example of a physical property?(Select all that apply)
boiling point density magnetism
Read the statement. A mixture is composed of three liquids with varied density. What is the most effective method of separation for this mixture?
centrifugation
What did the plum-pudding model explain about the structure of an atom?
that electrons have a negative charge and are dotted throughout a uniformly distributed, positively charged atom
Examine the table. Element Number of Protons Number of Neutrons Number of Electrons copper (Cu) 29 35 29 iodine (I) 53 74 53 francium (Fr) 87 136 87 lead (Pb) 82 125 82 Which element in the table has the greatest atomic mass?
francium
What piece of laboratory equipment would be used to transfer liquids to containers that have small openings?
funnels
Which option correctly defines precision?
how close the measurements are to each other
Which option accurately identifies the material that is a combination of two or more pure substances?
mixture
What is the subatomic particle that has no charge, but has mass?
neutron
Which option accurately describes how nuclear chemistry has affected society?(Select all that apply)
the ability to harness the power of nuclear fission has created a form of energy that is not dependent on fossil fuels. The use of radioactive isotopes to date fossils and artifacts has allowed modern society to better understand geological history. The devastation of the nuclear bomb in World War II has produced fear and distrust between countries that possess the knowledge and ability to make a nuclear bomb.
Which option accurately describes the property of volume?
the amount of space a substance's matter occupies
What is alchemy?
the ancient study of the behavior of nature with a focus on efforts to transform matter and discover a substance to attain immortality
What is the correct definition of chemistry?
the study of substances, their properties, and the changes they undergo
Read the scenario. A mass of a sample was recorded from an electronic scale as 9.20 g. How many significant figures are in the measurement recorded?
three
What were the major purposes of alchemy in medieval times? (Select all that apply)
to discover universal cures to diseases to discover a means to prolong life to transform base metals into gold (Au)
Which option provides a correct example of a derived unit in the SI system?
volume in cubic centimeters