Chem 115 Hw
There are about 5.3×10−6kg of quartz in a very fine sand grain. Write the number of kilograms of quartz in the sand grain in standard notation.
0.0000053 kg
The speed of light is around 6.706×108 miles per hour. What is the speed of light in units of miles per minute?
1.118×10^7 miles per minute.
A light-year is a measure of distance rather than time; it is the distance that a ray of light will travel in a year in a vacuum. The distance between the earth and the sun is approximately 0.0000158 light-years. Write this number in scientific notation.
1.58*10^-5 light years
How many groups are on the periodic table? a. 7 b. 10 c. 18 d. 30
18 groups The 18 groups are represented by the 18 columns on the table. Groups are labeled at the top of each column. In the United States, the labels were traditionally Roman numerals with capital letters. All columns, apart from the transition metals, are numbers from IA to VIIA. The transition metals (in the middle of the periodic table) are numbered from IB to VIIIB. However, IUPAC recommends that the numbers 1 through 18 be used, and these labels are more common.
Place the following steps of the scientific method in the correct order. 1.Hypothesis becomes theory. 2.Curiosity leads to observations. 3.Experiment is performed and results are consistent with prediction. 4.Hypothesis is created. 5.Additional testing is conducted and it supports hypothesis.
2, 4, 3, 5, 1
Use the periodic table below to answer the question that follows. What is the atomic mass of mercury? Your answer should have six significant figures. [ ]
200.592 amu Mercury has an atomic mass of 200.592 amu and an atomic number of 80.
If 1in.=2.54cm, calculate the number of inches in 75.0cm.
29.5 in
In the process of vision, the light-sensitive pigment rhodopsin undergoes cis-trans isomerism in response to light in about 2×10−10ms. How many seconds is this? Write the answer in scientific notation
2×10^ −13 s
Solve the following problem and report answers with appropriate number of significant digits: 1.31 cm×2.3 cm= _____
3.0 cm
Complete the following operation to the correct number of significant figures: 85.2÷25.90348=
3.29
Saltwater covers approximately 361,900,000 square kilometers of the earth's surface. Write the number of square kilometers of saltwater in scientific notation.
3.619*10^8 square kilometers
The distance between two towns is 40,000 meters. Write this value in scientific notation
4.0*10^4 m
A thermometer reads 25∘C. If the temperature in the room is then increased by 16 K, what temperature will the thermometer read, in degrees Celsius?
41 degrees Celsius The magnitude of 1K is equal to the magnitude of 1∘C. Therefore, this temperature can be found by adding the temperature change, in Kelvin, to the temperature in Celsius. 25C+16K=41C. Notice that the freezing temperature of water in Kelvin is 273.15K, and its boiling temperature 373.15K. The numerical difference in these two reference temperatures is 100, the same as for the Celsius scale.
Absolute zero in Celsius is −273.15C. Convert this to degrees Fahrenheit.
459.67 F
The wavelength of yellow light is approximately 0.000000580m. Convert this quantity from meters to nanometers.
5.80×10^2 nm
Complete the following operation to the correct number of significant figures: 4.5×11.41=
51
The coating on a pair of eyeglasses is about 0.5μm (micrometers) thick. Give this thickness in meters.
5×10^−7m
A meteorite was found to weigh 63,500 grams. How many kilograms is this?
63.5 kg
An object has a mass of 0.124kg and a volume of 1893mm3. What is its density in grams per cubic centimeter?
65.5 grams per cubic centimeter
How many significant figures does the number, 2098.00703 contain?
9
According to Ernest Rutherford, what percent of an atom is empty space? a. 99.95 b. 85.75 c. 95.98 d. 90.65
99.95 According to Ernest Rutherford the positive charges in the atom are highly condensed in the center of the atom, which was given the name "nucleus," and that the negatively charged electrons were far away, making the atom 99.95 percent empty space.
Students in a kindergarten class were each given a ball of sculpting clay with identical masses. Emily used all of her clay to make a ball, and Sarah used all of her clay to make a toy pony. Which of the following statements is true? a. emilys ball has less mass than sarahs pony b. sarah's pony has less mass than emily's ball c. both clay items have the same mass d. it's impossible to determine
Both clay items have the same mass. The law of conservation of matter tells us that as matter changes forms, mass is conserved. If both of the girls each used all of their clay (which began with identical masses), then each item will have the same mass as in the beginning.
A compound is a chemical substance composed of two or more kinds of elements in a fixed ratio. By what means can the components of a compound be separated? a. chemical means b. physical means c. chemical or phsyical neeed
Chemical means A compound cannot be separated into its component elements by physical means, but it can be separated into elements by chemical means.
Why is the term "chemical-free" when used to market cleaning products misleading?
Even naturally occurring substances are chemicals: The term "chemical-free" is misleading because all substances are made up of chemicals. Even natural-based cleaners like vinegar or baking soda are chemical compounds. The term is used only to sell products and plays on the misconception that chemicals are toxic.
Why are chemists interested in studying thermochemistry? Select all that apply. [ ]Heat is often absorbed during reactions. [ ]Heat is often released during a chemical reaction, but never absorbed. [ ]Heat is often released during chemical reactions. [ ]Heat is often absorbed in a chemical reaction, but never released.
Heat is often absorbed during reactions Heat is often released during chemical reactions Heat is often absorbed and released during chemical reactions as a way of energy changing forms. Therefore, chemists study thermochemistry as a way to understand what is happening during certain chemical reactions.
Which of the following shows a model of the atom consistent with J.J. Thomson's Plum Pudding Model?
In 1904, Thomson proposed the "plum pudding" model of the atom. In his comparison, the negative electrons were represented by the raisins in the pudding and the dough contained the positive charge.
Identify the postulate of atomic theory that is violated by the following set of observations: 59.95% of one sample of pure titanium dioxide is titanium; 62.10% of a different sample of pure titanium dioxide is titanium. a. an atom is the smallest unit of an element that can participate in a chemical change b. an elements consists of only one type of atom c. atoms of one element differ in properties from atoms of all other elements d. In a given compound, the atoms of its constituent elements are always present in the same ratio. e. atoms are neither created or destroyed during a chemical change, but instead are rearranged to yeild substances tha differ from those present before the change
In a given compound, the atoms of its constituent elements are always present in the same ratio. This statement violates the postulate: in a given compound, the numbers of atoms of each element always have the same ratio. Since the first sample of titanium dioxide was 59.95% the second sample must have the same percentage of titanium, thus it cannot contain 62.10% titanium. This is because the titanium to oxygen ratio must be the same in both samples.
Why is chemistry important?
It helps us explain other aspects of science, it is the central science, and we use it to study both small and large aspects of our universe.
Millikan utilized specific numerical data gathered by a. J.J. Thompson b. John Dalton c. Ernest Rutherford d. all of the above
J.J. Thomson Millikan used J.J. Thomson's charge-to-mass ratio for the electron to determine the mass of the electron.
Millikan utilized specific numerical data gathered by: a. J.J. Thompson b. Dalton c. Rutherford d. all of the above
J.J. Thomson Millikan used J.J. Thomson's charge-to-mass ratio for the electron to determine the mass of the electron.
Who was the first person to show strong empirical evidence for the existence of atoms? a. democritus b. albert einstein c. john dalton d. aristotle
John Dalton John Dalton is the father of modern atomic theory.
Which of the following events fail to follow the law of conservation of matter? a. burning wood for a fire b. freezing water into ice cubes c. the decomposition of MgCl2 into Mg and Cl2 d. none of these
None of these All of these events follow the law of conservation of matter.
Use the periodic table below to answer the question that follows. Which of the following are valid chemical symbols? Select all that apply. [ ] O [ ] He [ ] F [ ] Ua
O He F O (oxygen), He (helium), and F (fluorine) are all valid chemical symbols. Ua is not a valid chemical symbol, as no corresponding element exists.
Which of the following careers would require the use of chemistry on a daily basis? a. pool operator b. nature conservationist c. surveyor d. civil engineer
Pool operators need to understand how to check and monitor chemicals within the pool to ensure that the chlorine levels are safe. This is something that they would check daily and requires a knowledge of how chemicals react to each other.
Whose experiment measured the charge of the electron, allowing the mass of the electron to also be determined when combined with earlier results on the charge to mass ratio of the electron? a. J.J. Thompson b. John Dalton c. Ernest Rutherford d. Robert Millikan
Robert Millikan Robert Millikan discovered the charge of the electron in his oil drop experiment. Using the existing charge-to-mass ratio for the electron, he was able to then calculate the mass of the electron.
What model for the atom was proposed by Hantaro Nagaoka? a. plum pudding model b. solar system model c. nuclear model d. saturn-like model
Saturn-like model Nagaoka imagined the atom as a sphere of positive charges surrounded by a ring-like halo of electrons, strongly resembling the planet Saturn.
The international metric system used in science, medicine, and industry is known as
System of International Measurement
Which of the following was Robert A. Millikan able to determine, either from his own work, or by building on the work of J. J. Thomson? Select all that apply. [ ] the existence of an electron [ ] the charge of an electron [ ] the mass of an electron [ ] the model of an atom with a small, positively small nucleus
The charge of an electron. The mass of an electron Millikan was able to measure the charge of individual electrons, and was also able to determine the mass by combining his result with Thomson's measurement of the charge to mass ratio of the electron.
Which of the following did J.J. Thomson determine as a result of his cathode ray experiments? a. The existence of a small (lighter than an atom), negatively charged fundamental particle called the electron. b. the chrage of an electron c. the mass of an electron d. the model of an atom consisting of small , positively charged atoms in the nucleus
The existence of a small (lighter than an atom), negatively charged fundamental particle called the electron. J.J. Thomson's work led to the discovery of the electron.
How is it possible that energy is always conserved, but we are always saying we need to "conserve more energy"? a. the total amount of energy in any process varies b. the total amount of energy in any process decreases c. the total amount of energy in any process is fixed d. the total amount of energy in any process increases
The total amount of energy in any process is fixed. When we say energy is always conserved we mean the total amount of energy in any process or reaction never changes - it is fixed. When we tell ourselves to conserve energy we mean to use less of it by doing things like driving more fuel efficient cars, or insulating our houses better.
True or false: In science, a theory is best defined as "a well-supported, comprehensive, and testable explanation of an aspect of the natural world."
True While a lays person may define theory as "a point of view," or a "speculation," scientists use the term to describe a well-substantiated explanation of some part of nature. These explanations are repeatedly tested, verified, and confirmed through the process of the scientific method.
True or false: the study of science has been organized into multiple fields, because it is too multifaceted to be studied as a whole.
True; as the scientific method developed and our knowledge of the world around us expanded, it became necessary to organize scientific studies into more specific groupings such as physics, chemistry, biology, etc.
A pure substance that can be broken down by chemical changes is known as: a. an element b. an atom c. a compound d. a mixture
a compound A pure substance that can be broken down by chemical changes is known as a compound. An element is a pure substance that cannot be broken down by chemical changes. An atom is not a type of substance. It is a component of matter. A mixture is not a pure substance
Which statement BEST explains why temperature is an intensive property? a. It is a property that is independent of the amount of matter in a sample. b. It is a property that depends on the amount of matter in a sample. c. It is a property that is only viewable when a substance is undergoing a chemical reaction. d. It is a property that is dependent on the chemical properties of the matter.
a. It is a property that is independent of the amount of matter in a sample Temperature is an intensive property because it is independent of the amount of matter for a given sample.
water is: a. a proton b. an element c. an atom d. a molecule
a molecule Water is a molecule because it is made up of 3 atoms that are chemically bonded to each other.
Use the periodic table below to answer the question that follows. The reason that atomic numbers are always integer values is because every element has: a. a particular number of electrons b. a particular number of protons c. a particular number of neutrons d. a particular atomic mass
a particular number of protons The atomic number refers to the number of protons in an atom, which is always a specific number for a given element.
Crystal measures the mass of a beaker containing ice cubes and finds that its mass is 130 g. After an hour, the ice cubes have melted, and Crystal decides to take another measurement. What will be the mass of the beaker and the water? a. 130mg b. 100 mg c. 65mg d. there is not enough information to answer this question
a. 130 g According to the law of conservation of matter, state transformations do not change the mass of a substance. Therefore, the beaker with ice or water will have the same mass.
A tiny gas bubble in a carbonated beverage contains 2.69×1012 carbon dioxide molecules. Write the number of molecules in standard notation. a. 2,690,000,000,000 b. 0.00000000000269 c. 269,000,000,000,000 d. 269,000,000,000
a. 2,690,000,000,000
There are 4 gleeks in a glook, 7 glooks in a gluck, and 5 glucks in a glack. How many gleeks are in 4glacks? a. 560 b. 140 c. 20 d. 0.03
a. 560
Carbon dioxide has a density of 2.0gL. What mass will a 3.5 L sample of carbon dioxide have? a. 7.0 g b. 0.57 g c. 1.8 g d. 1.1 g
a. 7.0 g
Which of the following is true? a. A law is formed when testing yields constant observations. b. A law is formed when additional testing supports the hypothesis. c. A theory is formed when testing yields one observation. d. A theory is formed when testing yields multiple observations.
a. A law is formed when testing yields constant observations.
When converting from Celsius to Kelvin, one should always: a. Add 273.15 b. Subtract 273.15 c. Convert to Fahrenheit first d. Divide by 59
a. Add 273.15 Converting from Celsius to Kelvin requires the addition of 273.15. These units exhibit a linear relationship where 273.15 is the y-intercept.
Britta traveled 1250 km on her road trip and used 209 L of gasoline, filling her tank at an average cost of 1.14 euros per liter. Pierce traveled 1405 km on his trip and used 175 L of gasoline, filling his tank at an average cost of 1.23 euros per liter. Who paid more per kilometer driven for their trip? a. Britta b. Pierce c. They paid the same amount d. There is not enough information to answer this question.
a. Britta
Alpha particles have: a. positive charge b. negative charge c. no mass d. none of the above
a. positive charge Because alpha particles have a positive charge, Rutherford was able to gain the insights he did in his gold foil experiments.
Which of the following statements about the scientific method is true? a. It is a systematic approach to research. b. It begins with performing an experiment. c. A hypothesis is formed at the end of the the process. d. The process provides the basis for the formation of laws.
a. It is a systematic approach to research. The scientific method begins with observation and curiosity and provides a systematic approach to experimentation and scientific research.
Which of the following must be true about a precise measurement? a. It typically contains many significant figures. b. It has very few significant figures. c. It is very close to the true value. d. It is far away from the true value.
a. It typically contains many significant figures.
A child on a sled starts at the top of a hill with 90 J of potential energy. At the bottom of the hill, she has only 55 J of kinetic energy. Assuming that at the top of the hill she has only potential energy and at the bottom she has only kinetic energy, what can we conclude? (Remember, potential energy is the energy of position while kinetic energy is the energy of motion.) a. work must have been done b. the child is not good at sledding c. at some point the child hesitated going down the hill d. the child sled down one hill but is about to up another
a. Work must have been done. There was a change in the amount of energy so work must have been done. Motion is definitely indicated which shows work has been accomplished. The other 3 choices are assumptions which cannot be empirically obtained in this problem.
A large change in temperature (not resulting from external heating) with the appearance of gas bubbles is most likely an indication of: a. a chemical change b. only physical changes occur c. molecules are going under physical change d. none of the above
a. a chemical change A large change in temperature with the appearance of gas bubbles indicates that a chemical change has most likely occurred.
A scientific theory is best described as a. a comprehensive, substantiated, and testable explanation of how nature works b. a guess that a person makes c. a summary of a vast number of experimental observations d. a testable prediction to answer a specific question
a. a comprehensive, substantiated, and testable explanation of how nature works A comprehensive, substantiated, and testable explanation of how nature works is known as a scientific theory. Hypotheses are testable predictions that answer a specific question. Laws are a summary of a vast number of experimental observations
In November 2018, the kilogram was redefined in terms of Planck's constant. Directly prior to this, the kilogram was based on: a. a cylinder of platinum-iridium alloy b. the mass of a liter of water c. the mass of a king's crown d. the mass of a gold bar
a. a cylinder of platinum-iridium alloy The kilogram was originally defined to be the mass of one liter of water; however, there is some variance in this quantity with temperature and pressure. A more rigid definition for the kilogram was adopted In the late 19th century, which defined the mass of one kilogram as the mass of a metal cylinder of platinum-iridium alloy, which is stored in France.
Which operation is performed to convert a temperature given in degrees Celsius to a temperature in kelvin? a. add 273 b. subtract 273 c. multiply by 273 d. divide by 273
a. add 273 Kelvin and Celsius have a linear relationship, but not a proportional relationship. They do not have the same starting point, but they increase at the same rate. 0 K is absolute zero, which is about −273∘C, so to get Kelvin from Celsius, add 273.
Which object has the most gravitational potential energy? a. an airplane in mid-flight b. a baseball held by a pitcher c. a bird on top of a flagpole d. these objects all have the same gravitational potential energy
a. an airplane in mid-flight An object's gravitational potential energy increases with increasing height and with increasing mass. Thus the plane, having both the highest altitude and greatest mass, will have the greatest potential energy.
When adding numbers, the sum will have: a. as many decimal places as the number with fewest decimal places b. as many decimal places as the number with the most decimal places c. as many significant figures as the number with fewest significant figures d. as many significant figures as the number with the most significant figure
a. as many decimal places as the number with fewest decimal places
Which of the following is true according to Dalton's atomic theory? a. atoms cannot be created or destroyed. b. atoms the same element will have different sizes and masses c. elements can consist of many types of atoms d. all of the above
a. atoms cannot be created or destroyed. Dalton's atomic theory states that atoms can not be created or destroyed. This is consistent with the law of conservation of matter. If a chemical change is simply the rearrangement of atoms, and atoms are not created or destroyed when participating in a chemical change, this explains how matter is conserved in any chemical reaction.
Which prefix means one one-hundredth? a. centi b. deci c. milli d. kilo
a. centi
If object A and object B have the same density, but object A has greater mass, then object A must have: a. greater volume b. smaller volume c. the same volume d. can't be determined
a. greater volume If these objects have the same density, that means they have the same ratio of mass to volume, so a greater mass must also mean a greater volume.
Which of the following is an example of an endothermic process? a. melting ice cubes b. burining sugar c. a candle burning d. condensation of rain to water vapor
a. melting ice cubes Melting ice cubes are an example of an endothermic process. The ice cubes absorb heat energy from the air around them and any other object (with more thermal energy than the ice cubes) with which they may be in contact. Burning sugar and a candle burning are both chemical reactions which give off heat energy, so they are both exothermic. When water vapor condenses, more energetic gas molecules become less energetic liquid molecules; the heat energy from the more energetic molecules in the gas phase is given off to the environment, making it an exothermic process.
A temperature change of one degree kelvin is the same magnitude as a change of a. one degree Celsius b. one degree Fahrenheit c. both one degree Celsius and Fahrenheit d. none of the above
a. one degree Celsius
The number of significant figures in a value is a display of the _________ of a measurement a. precision b. accuracy c. both precision and accuracy d. none of the above
a. precision Accuracy is a measure of how close a measurement is to a true or accepted value, whereas precision is a measure of how well consecutive measures of the same quantity agree with one another. The number of significant figures in a value will provide information regarding the precision of the value. For example, 15.000mL is a more precise value than 15mL. Significant figures alone will not provide evidence to suggest that a measured value is close to the true or accepted value.
According to Rutherford, the nucleus of an atom must contain: a. protons b. electrons c. protons and electrons d. none of the above
a. protons The gold foil experiments gave evidence for a nucleus containing protons in every atom of gold, and consequently all atomic matter.
Which of the following is NOT considered a SI unit of measurement? a. the pound b. the meter c. the kilogram d. the second
a. the pound
Use the periodic table below to answer the question that follows. The symbol Fe could refer to which of the following? Select the best answer below. a. an iron atom b. the element "iron" c. a macroscopic sample of iron d. all of the above
all of the above Fe means "iron" and it can be used to represent an individual iron atom in a molecular formula, or a ratio of iron atoms to other elements or compounds in a reaction, or just to represent the element itself without reference to any specific sample of iron.
Which of the following is a molecule? a. water b. ozone c. glucose d. all of the above
all of the above Water, ozone, and glucose are all molecules, as they are all comprised of more than one atom.
What is the SI unit of "mole" used to measure?
amount of a substance
The smallest particle of an element that has the properties of that element is called a(n): a, proton b. electron c. an atom d. a molecule
an atom The atom is the smallest unit of an element. A proton and electron are subatomic, and a molecule is a combination of atoms.
Which of the following can only consist of only one kind of atom? a. an element b. a pure substance c. a compound d. a mixture
an element Elements consist of only one kind of atom. Compounds and mixtures consist of more than one type of atom. A pure substance is either an element or a compound, so it could consist of one type of atom, but it does not have to.
Convert from one unit to the other: 2.69 Joules to calories (1.000 cal=4.184 J). a. 11.3 calories b. 0.643 calories c. 1.56 calories d. 0.372 calories
b. 0.643 calories There are 4.184 joules in 1 calorie. So, divide 2.69 by 4.184 which equals 0.643 calories.
What is 50F converted to C and K? a. −4C, 263 K b. 10C, 283 K c. 32C, 273 K d. 45C, 240 K
b. 10C, 283 K
One year consists of 365 days. This is closest to how many seconds? a. 31.5 kiloseconds b. 31.5 megaseconds c. 31.5 gigaseconds d. 31.5 teraseconds
b. 31.5 megaseconds
Which of the following measurements would be a reasonable guess for the diameter of a gold atom? a. 3e8 m b. 3e-10 m c. 3e5 m d. 3e-5 m
b. 3e-10 Atoms are microscopic particles that require specialized microscopes to visualize. Of the four lengths presented, only 3e−10 m fits this description. The next shortest length, 3e−3 m, is equal to 3 millimeters and can be seen by the naked eye.
Convert 0.006734 into scientific notation. a. 6.734×10 b. 6.734×10−3 c. 6.734×10^3 d. 6734×10−3
b. 6.734×10−3
Which of the following statements BEST describes the SI system of unit? a. An updated version of the English System of Measurement. b. An expansion of the metric system. c. Another version of the Imperial System of Measurement. d. The only system of measurement that is used throughout the world.
b. An expansion of the metric system
The temperature scale we use most frequently in chemistry labs is: a. Fahrenheit b. Celsius c. Kelvin d. none of the above
b. Celsius The Kelvin scale is used most often in equations because it is an absolute temperature scale, but Celsius is most often used in the lab. Fahrenheit is rarely used in the field of chemistry.
What is significant about the temperature of 0K? a. It is the temperature at which matter has no density. b. It is the temperature at which atoms stop moving. c. It is the temperature at which atoms cease to exist. d. It is the temperature at which water molecules freeze
b. It is the temperature at which atoms stop moving.
How are organic light emitting diodes (OLEDs), used in many modern displays, related to chemistry? a. Chemistry helped to discover what OLEDs were. b. OLEDs use new materials that were developed using chemistry. c. Chemistry is critical in marketing the new materials. d. The displays are needed to continue to study chemistry.
b. OLEDs use new materials that were developed using chemistry Organic light emitting diodes (OLEDs) are synthesized compounds that are now used in many displays. Chemistry played a role in determining methods for creating these compounds.
0.738×0.28 is 0.20664 but is rounded to 0.21. Which rule or rules are applied to this calculation? Select all that apply. a. Round the result to the same number of decimal places as the value with the least number of decimal places. b. Round the result to the same number of significant figures as the value with the least number of significant figures. c. Round down if the digit to be dropped is less than 5. d. Round up if the digit to be dropped is 5 or greater.
b. Round the result to the same number of significant figures as the value with the least number of significant figures. d. Round up if the digit to be dropped is 5 or greater.
Which of the following is NOT a unit used in the SI system? a. ampere b. atomic mass unit c. kilogram d. meter
b. atomic mass unit
In some cases, volume can be found by cubing which of the following quantities? a. mass b. length c. time d. none of the above
b. length Volume can be considered length times width times height, or a length in each of three spatial dimensions.
Matter that will take the shape of its container, but not expand to fill it is in what phase? a. solid b. liquid c. gas d. none of the above
b. liquid Liquids have a definite volume, but no definite shape. This means that they will expand to fit the shape of their container, but not expand to fill it completely.
Which of the following is NOT a base unit used in the SI system of measurement? a. second b. milliliter c. mole d. meter
b. millitier
Which is the shortest length of time? a. one microsecond b. one nanosecond c. one millisecond d. one decisecond
b. one nanosecond
What physical state of matter is associated the particles having least amount of thermal energy? a. gas b. solid c. liquid d. All phases of matter contain the same measure of thermal energy.
b. solid Solids have the most rigidly packed particles (molecules, ions, or atoms) because they have the lowest amount of thermal energy compared to the other states of matter for that substance.
Which of the following is measured using Newtons (a unit of force)? a. mass b. weight c. density d. volume
b. weight Weight is measured using newtons, a unit of force.
A speed limit in a U.S. city is 65.0 miles per hour. Canadian cities express speed limits in kilometers per hour. Express the value in km/hr. (1.609 km=1 mile) a. 100km/hr b. 102km/hr c. 105km/hr d. 110km/hr
c. 105km/hr
The circumference of the earth is approximately 40 million meters. This is closest to: a. 40 picometers b. 40 kilometers c. 40 megameters d. 40 gigameters
c. 4o megameters
If the accepted value for a measurement is 60.3 mL, which of the following sets of measurements is precise but not accurate? a. 56.7 mL, 87.3 mL, 28.9 mL b. 60.2 mL, 60.3 mL, 60.1 mL c. 76.5 mL, 76.4 mL, 76.3 mL d. all of the above
c. 76.5 mL, 76.4 mL, 76.3 mL The measurements that are close together but not close to the true value will be the set that can be considered precise but inaccurate.
In which temperature scale is the boiling point of water represented by the largest number? a. Celsius b. Fahrenheit c. Kelvin d. The number stays the same in all units.
c. Kelvin The boiling point of water is 100 Celsius, 212 Fahrenheit, and 373 Kelvin. Therefore the boiling point of water is represented by the largest number on the Kelvin scale.
Object A has a density of 2.0 g/cm3 and a mass of 100 g. Object B a density of 0.8 g/cm3 and a mass of 240 g. Object C a density of 5.0 g cm3 and a mass of 100 g. Which of the objects above (A, B, or C) has the smallest volume? a. Object A b. Object B c. Object C d. all of the objects have the same volume
c. Object C
Which of the following is a rule of significant figures in calculations? a. Round the result to the same number of digits as the number with the most number of significant figures. b. Round up if the digit to be dropped is less than 5. c. Round down if the digit to be dropped is less than 5. d. None of the above.
c. Round down if the digit to be dropped is less than 5.
Why is chemistry helpful in understanding how a toaster creates the brown color and crispy texture of toast? a. The properties of the bread molecules are changing in the toaster. b. The toaster uses electricity. c. The composition and/or properties of the surface of the toast are somehow changed by the toaster. d. The process takes place in the atmosphere.
c. The composition and/or properties of the surface of the toast are somehow changed by the toaster. Chemistry is related to the study of matter -- its properties and interactions. The bread molecules are changing when they are exposed to the heat of the toaster.
Which of the following gives all of the information necessary to determine the number of subatomic particles? a. mass number b. atomic number c. atomic symbol d. element name
c. atomic symbol The atomic symbol includes the elemental symbol, the atomic number and the mass number. The latter two are the number of protons and the sum of the number of protons and neutrons, so it is possible to find the number of neutrons by subtracting atomic number from mass number.
When an object's temperature __________, it will most likely contract. a. increases b. remains constant c. decreases d. none of the above
c. decreases When an object's temperature decreases, it will most likely contract. Most (but not all) substances behave this way.
Which of the following is NOT a field of study that would require chemistry? a. genetics b. technology c. education d. medicine
c. education; chemistry aids in the understanding of STEM disciplines. Genetics, technology, and medicine would all require chemistry. The E in STEM stands for engineering, not education.
A single bee weighs 0.00025 pounds which equals 0.113398 ______. a. milligrams b. centigrams c. grams d. kilograms
c. grams A single bee weighs 0.00025 pounds which equals 0.113398 grams. A milligram is a thousandth of a gram so that unit is too small. A centigram is one hundredth of a gram. A kilogram equals 1000grams because the prefix kilo means 1000.
A hot object is associated with __________ thermal energy, and the heat will flow from a __________ object to a __________ object. a. low; hot, cold b. low; cold, hot c. high; hot, cold d. high; cold, hot
c. high; cold, hot Thermal energy is the kinetic energy associated with the random motion of atoms and molecules. In a hot object, the particles are moving more quickly than they would in a cold object. Additionally, heat is the exchange of thermal energy, and heat will always flow from a hot object to a cold object.
Which of the following is NOT a SI base unit? a. m b. s c. oz d. cd
c. oz
The digits in a measurement, including the uncertain last digit, are known as: a. uncertainity digits b. precise measurements c. significant figures d. none of the above
c. significant figures
If you were on the moon, which has significantly less mass than the earth, your mass would: a. increase b. decrease c. stay the same d. become zero
c. stay the same Your mass does not change because of where you are in a gravitational field, it is an inherent characteristic of matter
Which of the following is NOT a likely indicator of a chemical change? a. the formation of precipitate b. a color change c. the change of shape of a malleable metal d. the release of gas without adding heat or lowering pressure
c. the change in shape of a malleable metal The bending of a piece of metal, like a paper clip, is not a chemical change. Only when a new substance is formed, evidenced by a new material present or a change in color, can a chemical change be guaranteed.
In Ernest Rutherford's gold foil experiment, why did alpha particles sometimes (1 in 8,000) fly violently in a random direction? a. the negative alpha particles were perfectly aligned to strike a nucleus b. the alpha particles moved eratically naturally c. the positive alpha particles were perfectly aligned to strike a nucleus d. none of the above
c. the positive alpha particles were perfectly aligned to strike a nucleus Positively charged alpha particles typically pass right through, but if they are just perfectly aligned to strike a nucleus the huge repulsion between the positive charges makes them fly violently in a random direction.
For a number written in scientific notation, 1.02×10^−7, what does the exponent represent? a. the amount of zeros to add to the digit term b. how many times to multiply the digit term by itself c. the power of ten the digit term is multiplied by d. reliability of the digit term to the accepted value
c. the power of ten the digit term is multiplied by In scientific notation, the digit term (also known as the mantissa) is the number before the times symbol, and it gives the precise value of the number. The exponent (b) gives the order of magnitude of the number (power of 10) and can be used to count the number of decimal shifts from the mantissa to write the number in standard notation.
If you boil a sample of water, the steam that results will have: a. less mass than the water b. more mass than the water c. the same mass d. impossible to predict
c. the same mass The law of conservation of matter tells us that mass is conserved as matter changes forms. Therefore, all the water molecules in the steam will have the same mass as when they were in the liquid form.
If a hypothesis is shown to be accurate after multiple tests, then a. it becomes a law b. it will never be proven incorrect c. there is still a chance that it could be proven wrong d. it can be applied to multiple observations
c. there is still a chance that it could be proven wrong Even if a hypothesis is shown to be accurate after multiple tests, there is still a chance that it could be proven wrong.
When computing using dimensional analysis: a. all unit conversions must be done separately b. all unit conversions must be done in a singular calculation c. unit conversions can be done either simultaneously or separately d. unit conversions are not a part of dimensional analysis
c. unit conversions can be done either simultaneously or separately We can perform unit conversions one at a time or many at a time, just be sure to keep in mind that this could create a discrepancy in the number of significant figures in your result, depending on when you decide to round your value.
________________ depends on ________________. a. scalar, vector b. vector, scalar c. weight, mass d. mass, weight
c. weight, mass Weight is the force that a gravitational field exerts on an object, and this depends on the mass or amount of matter present in the object: W=mg.
Which of the following temperatures are equivalent to absolute zero (0 K)? Select all that apply. a. 74.93∘F b. −100∘C c. −273.15∘C d. −459.67∘F
c. −273.15∘C & d. −459.67∘F
The kind of energy stored within the bonds of molecules is called: a. kinetic energy b. joules c. elctromagnetic energy d. chemical potential energy
d. chemical potential energy The energy stored within covalent chemical bonds is called chemical potential energy, which is what is used to power our bodies in their day-to-day motion.
The charges on the proton and electron are typically measured in: a. volts b. amperes c. daltons d. colombs
d. colombs
Which of the following CANNOT be classified as a compound? a. carbon dioxide b. sodium chloride c. lithium d. sugar
lithium Lithium is an element. The rest are made of multiple elements.
A liter is equivalent to: a. 1 cm3 b. 1 m3 c. 1 mm3 d. 1 dm3
d. 1 dm3 Use the fact that 1mL=1cm3 to determine the equivalent volume of 1L. If 1mL=1cm3, then 1L=1,000mL=1,000cm3. Now, convert 1,000cm3 into m3. 1,000cm3×(1m100cm)3=1×10−3m3 Now, use the fact that 1m=10dm to determine the volume of 1dm3 in m3. 1dm3×(1m10dm)3=1×10−3m3 Therefore, 1L=1×10−3m3=1dm3.
35 gigatons equals __________. a. 3.5×10−9tons b. 3.5×10−10tons c. 3.5×109tons d. 3.5×1010tons
d. 3.5×1010tons The prefix "giga" means 109, so it can be written as the following. 35gigaton=35×109tons To write the number in scientific notation, the decimal part must be between 1 and 10. Move the decimal point in 35 to the left one place, and, since this makes the number smaller by a power of 10, add 1 to the exponent on 10 to compensate. 35×109tons=3.5×1010tons.
Whose view that matter as infinitely divisible was considered correct for most of the last two millenia? a. Democritis b. Einstein c. John Dalton d. Artistotle
d. Aristotle Aristotle believed that everything was comprised of earth, air, water, and fire, which were infinitely divisible.
Which is the longest distance? a. a meter b. a kilometer c. a megameter d. a terameter
d. a terameter
According to Dalton's theory, atoms of a given element are: a. identical in mass b. extremely tiny c. different from atoms of any other element d. all of the above
d. all of the above These three statements are at the core of Dalton's atomic theory.
Which of the following states of matter can exert pressure? a. solid b. liquid c. gas d. all of the above
d. all of the above All the phases of matter can exert pressure.
What did Ernest Rutherford's work uncover? a. the existence of the electron b. the fundamental charge c. the mass of an electron d. an improved model of the atom
d. an improved model of the atom Rutherford's work helped improve the model of the atom. He discovered that atoms consist of a small charged nucleus surrounded by tiny electrons, and are mostly empty space.
Where would you be "weightless"? a. the Moon b. the Sun c. the bottom of the ocean d. deep space
d. deep space Only in deep space, far away from any source of gravity, would there be no gravitational force to give your body any weight. You would still have mass, but you would be effectively weightless.
"The higher the pH of the water in a pond, the higher the algae growth." This statement is an example of a _____________. a. law b. theory c. fact d. hypothesis
d. hypothesis
Which best characterizes the following statement: Energy is never created nor destroyed. a. observation b. hypothesis c. theory d. law
d. law
Which of the following is not reliant on an understanding of chemistry? a. geology b. biotechnology c. agriculture d. mathematics
d. mathematics Geology, biotechnology, and agriculture all rely on chemistry in their study and application.
Which of the following units is a derived SI unit (not one of the SI base units)? a. meter b. kilogram d. second d. newton
d. newton
Despite the units frequently seen on laboratory scales, the most appropriate unit below for quantifying weight is _______. a. kelvin b. grams c. amperes d. newtons
d. newtons Newtons measure force, and weight is the force exerted by an object because of its position in a gravitational field. Kelvin measures temperature, grams measure mass, and amperes measure electrical current. Most laboratory scales purport to measure mass and display grams (or kilograms or milligrams) rather than newtons, because it is assumed that they will be used on Earth and most chemists would need to convert the weight to a mass anyway.
What is not a scientific discipline that chemistry is related to? a. toxicology b. food science c. nanotechnology d. philosophy
d. philosophy
In dimensional analysis, what is a conversion factor? a. accepted values for physical quantities b. theoretical quantities of matter c. experimental values for given quantities of matter d. ratios of physical quantities used to compare desired units
d. ratios of physical quantities used to compare desired units Conversion units are ratios of physical quantities used to compare between two desired units. They are not experimental or theoretical.
Which of the following can be characterized as a physical change? a. Iron pipe rusts b. milk goes sour c. fire burning d. sweat evaporates off your skin
d. sweat evaporates off your skin Sweating is an example of a phase transition (from liquid to gas) which is a physical change. An iron pipe rusting, milk turning sour, and firewood burning are examples of chemical changes.
Today, the meter is based on: a. a meter stick b. the height of a king c. a fraction of the distance from the equator to the north pole d. the distance light travels in a particular fraction of a second
d. the distance light travels in a particular fraction of a second
Which of the following objects has more kinetic energy than it does potential energy? a. compressed spring in a pinball machine just before the ball is launched b. a rollercoaster motionless at the top of a track c. a yo-yo before it is released d. the pendulum of a grandfather clock at the lowest point of its arc of motion
d. the pendulum of a grandfather clock at the lowest point of its arc of motion the pendulum of a grandfather clock at the lowest point of its arc of motion Kinetic energy is the energy of motion. Each of the objects above are motionless—with stored potential energy—except for the clock. At the bottom of its arc it will have the greatest kinetic energy, which is then converted to potential energy as it swings back up to one side.
Which of the following is an example of encountering chemistry in daily life? a. an apple falling to the ground b. the moon creating high and low tides at the shore c. solving a complex problem using calculations d. using a filter to make coffee
d. using a filter to make coffee; Chemistry is the study of the composition, properties, and interactions of matter. Using a filter when making coffee is using knowledge of how to separate the mixture of coarse coffee grounds and water to be left with the liquid coffee.
Information collected during an experiment is called
data
A homogenous mixture varies from a heterogenous mixture in that a homogenous mixture has properties that: a. do not vary in the mixture b. vary in the mixture c. suspend in a liquid d. dissolve a solute
do not vary in the mixture A homogenous mixture varies from a heterogenous mixture in that a homogenous mixture has a uniform composition.
According to modern atomic theory, atoms consist mostly of a. empty space b. negatively charged electrons c. positively charged electrons d. a positively charged nucleus
empty space Ernest Rutherford's gold foil experiment showed that atoms are made mostly of empty space that surrounds a dense, positively charged nucleus.
When a substance undergoes a chemical reaction, which of the following will NOT change? (select all that apply). [ ] temperature [ ] energy [ ] density [ ] mass
energy mass Due to the Law of Conservation of Energy (energy can be neither created or destroyed) and the Law of Conservation of Mass (there is no detectable change in the total amount of matter during a chemical change), neither energy nor mass has detectable change when undergoing a chemical reaction. The total quantity of matter and energy in the universe is fixed.
Of the two classifications for mixtures, which of the following represents a mixture with a uniform composition throughout? a. binary mixture b. homogeneous mixture c. heterogeneous mixture d. pure mixture
homogeneous mixture Of the choices listed, a homogeneous mixture is one of the two classes of mixtures. The second is a heterogeneous mixture. A homogeneous mixture has a uniform composition of its components throughout.
A tentative explanation of observations that acts as a guide for gathering and checking information is called a
hypothesis
Characterize the following statement: If you drink coffee before going to bed, it will take longer to fall asleep.
hypothesis This can best be described as a hypothesis because it is an idea or prediction about the way things are that must be tested by experiment. If by excessive experiment a relationship is proven, a hypothesis can then become a theory or law.
Use the periodic table below to answer the question that follows. The noble gases are also called the: a. reactive gases b. inert gases c. lonely gases d. none of the above
inert gases Nobel gases are also known as inert gases because they are for the most part completely unreactive
Use the periodic table below to answer the question that follows. The chemical symbol "CL" with two capital letters is used to represent which element? a. Chlorigen b. Chlorine c. clorominium d. it's not a valid chemical symbol
its not a valid chemical symbol CL is not a valid chemical symbol because chemical symbols that contain 2 letters must have one upper case letter and one lower case letter, not 2 upper case letters.
Heat energy is measured in units of __________. (Select all that apply). [ ] degrees Celcius [ ] joules [ ] calories [ ] degrees Kelvin
joules calories The units we use for measurements of heat energy are calories or joules. Degrees Celsius and degrees Kelvin are units of temperature, not heat energy.
A pattern that has been established based on verified experimental data that describes an observation but does not provide an explanation as to the reason why said observation occurs is a _________
law A law is a pattern that has been established based on verified experimental data. Laws provide a description of a particular observation, but does not go so far as to explain why the observation occurs. For example, the law of conservation of energy states that energy is neither created nor destroyed but does not explain why this is the case.
J.J. Thomson's discovery of the electron relied on the observation that: a. like charges repel and unlike chrges react b. like charges attract and unlike charges react c. like and unlike charges repel d. like and unlike charged react
like charges repel and unlike charges attract J.J. Thomson's work relied on the observation that like charges repel and opposite charges attract.
For a given atom, which of the following is typically the largest in value? a. atomic number b. number of protons c. mass number d. all of the above are typicall equal
mass number The mass number is equal to the number of protons and neutrons in the nucleus. This is typically larger than the atomic number, which is equal to the number of protons. The only exception would be hydrogen, which will typically have an atomic number and mass number both equal to one.
Atoms of the same element can have different: a. atomic numbers b. mass numbers c. number of protons d. none of the above
mass numbers Atoms of the same element must have the same number of protons, as this defines their atomic number which is characteristic of that element. But they may have differing numbers of neutrons which would generate a different mass number.
Atoms of the same element can have different: a. atmoic numbers b. number of protons c. mass number d. none of the above
mass numbers By definition, atoms of a given element have a particular atomic number (which is the same as the number of protons), but they can have different mass numbers if they have differing numbers of neutrons.
Use the periodic table below to answer the question that follows. Elements in group 2 are: a. metalloids b. nonmetals c. metals d. all of the above
metals All elements in group 2 are metals. Metals are elements that are shiny, malleable, good conductors of heat and electricity.
J.J. Thomson's model for the atom was called the:
plum pudding model Thomson named it the plum pudding model because he imagined the electrons sitting in the positively charged matter like raisins suspended in plum pudding.
A set of measurements that yield very similar results when repeated in the same manner are said to be
precise
How does a mixture differ from a pure substance? a. pure substances are aesily separated into components, mixtures are not b. mixtures all have uniform compositions, pure substances do not c. pure substances have constant chemical and physical properties while mixtures are varied d. mixtures require chemical methods of separation while pure substances can be easily separated by physical means
pure substances have constant chemical and physical properties while mixtures are varied Mixtures can be classified as homogenous or heterogenous and can be separated into their component parts by chemical or physical means. Pure substances have constant chemical and physical properties while mixtures can be varied.
An example of homogeneous mixture is: a. muddy water b. pure water c. ice water d. saline water
saline water A homogeneous mixture has uniform composition for any given sample. A saline water solution has equal parts of salt dissolved throughout. Muddy water and ice water are heterogenous mixtures while pure water is a compound (and a pure substance)
What is another word for period? a. series b. group c. section d. family
series A period is also referred to as a series. The period, or series, groups elements based on their atomic orbitals.
In order to be valid, a hypothesis must be
testable
Use the periodic table below to answer the question that follows. Which of the following is used to abbreviate an element or an atom of a given element? a. the mass number b. the atomic mass c. the chemical symbol d. the atomic number
the chemical symbol An element is is a substance that cannot be broken down or changed. Each element is represented with a chemical symbol which is an abbreviation for the element or an atom of an element.
What is the standard SI unit of mass?
the kilogram
In his proposal of atomic structure, Rutherford drew which of the following conclusions? a. that like charges repel and unlike charges react b. the volume occupied by an atom must consist of a large amount of empty space c. the fundamental charge d. the atom is divisible
the volume occupied by an atom must consist of a large amount of empty space Rutherford concluded that the volume occupied by an atom must consist of a large amount of empty space.
A well-substantiated, comprehensive, testable explanation of a particular aspect of nature is called a(n)
theory
Characterize the following statement: All life on earth evolved by natural selection from a common ancestor.
theory
If a scientist wanted to determine the amount of space occupied by an object, she would measure its
volume