Q&A Hero

Q: Which of the following statements describes a polar molecule? A) The electrons in the molecule are distributed evenly throughout the molecule. B) The molecules are usually not attracted to one another very strongly. C) Polar molecules have the weakest intermolecular interactions with ionic compounds. D) The molecules have a high degree of symmetry. E) None of these statements describe polar molecules.

Q: Which of the following molecules has the highest boiling point? A) BH3 B) NH3 C) CH4 D) All of the above should have the same boiling point.

Q: Which of the above substances would have the largest dipole?A) aB) bC) cD) Each has the same size dipole.E) None of the molecules has a dipole.

Q: Which of the above substances would have the lowest boiling point?A) aB) bC) cD) All boil at the same temperature.E) All are gases.

Q: Which of the following molecules is polar?A) aB) bC) cD) All are polar.E) Only A and C are polar.

Q: Which is more polar, a sulfur-bromine (S-Br) bond or a selenium-chlorine (Se-Cl) bond? A) A selenium-chlorine bond should be more polar because of a greater difference in effective nuclear charge. B) A selenium-chlorine bond should be more polar because of a smaller difference in effective nuclear charge. C) A sulfur-bromine bond should be more polar because of a greater difference in effective nuclear charge. D) A sulfur-bromine bond should be more polar because of a smaller difference in effective nuclear charge.

Q: Nanoscience has shown that A) a chemical occurs with the use of a scanning probe microscope. B) the properties of a material can be different on the level of atoms then its properties when the material is analyzed in bulk. C) a physical change can occur when using a scanning probe microscope. D) DNA is the smallest molecule.

Q: The scanning probe microscope A) uses very large mirrors and lenses to enhance an image. B) can scan small things from a large distance away, such as the surface of the Moon. C) characterizes the surface atoms of a material. D) vaporizes a substance, then analyzes and manipulates the components.

Q: Nanotechnology may play an important role in the development of A) space elevators. B) windfarms. C) bullet proof clothing. D) a storage medium for hydrogen fuel. E) all of the above

Q: Some products on the market today involving nanotechnology include A) cars. B) elevators. C) sunscreen. D) cosmetics. E) all of the above

Q: Nanotechnology and microtechnology are similar in that they both A) are interdisciplinary. B) have huge impacts on society. C) are relatively new technologies. D) all of the above

Q: Nanotechnology looks at working with particles the size of A) 100 microns or larger. B) 1 to 100 nanometers, the realm of individual atoms and molecules. C) 50 grams and smaller. D) infinitesimally small, the size of electrons.

Q: Microtechnology began A) about 60 years ago with the invention of solid state transistors. B) in the 1990s with the use of computers. C) with the development of micron chemistry in the early 1800s. D) at the close of World War II.

Q: Compared to microtechnology, nanotechnology focuses on a scale that is about A) 10 times smaller. B) 100 times smaller. C) 1000 times smaller. D) a million times smaller.

Q: The probe tip of a scanning probe microscope A) floats above the atoms of a sample. B) etches into the atoms of a sample. C) chemically changes the atoms of a sample. D) injects a magnetic field into the atoms of a sample.

Q: In naming compounds, the prefix is used to A) indicate the level of toxicity. B) categorize the compound. C) indicate the relative number of atoms. D) indicate the relative number of molecules.

Q: Nitrogen dioxide and dinitrogen tetroxide are really A) the same compound. B) different compounds. C) not possible as compounds. D) best represented as NO.

Q: When two elements come together to form a compound, which element is named first within the name of the compound? A) The element coming first in the English alphabet. B) The element with the greater atomic mass. C) The element with the greater atomic number. D) The element toward the left hand side of the periodic table.

Q: What is the name of the following compound? NaF A) sodium fluoride B) natural fosfate C) natrium fluoride D) nitrogen afleck E) sodium phosphide

Q: What is the name of the following compound? CaCl2 A) calcium chloride B) carbon chloride C) dichlorocalcium D) calc two E) dicalcium chloride

Q: What is the name of the following compound? CO2 A) carbon dioxide B) dicobalt C) dioxocarbon D) calcium oxide E) calcium dioxide

Q: What is the name of the following compound? SF3 A) sulfur trifluoride B) sulfur fluoride C) trifluorosulphide D) fluorine sulphide E) none of the above

Q: The systematic names for water, ammonia, and methane are dihydrogen monoxide, O; trihydrogen nitride, N; and tetrahydrogen carbide, C. Why do most people, including chemists, prefer to use the common names for these compounds? A) The common names are shorter and easier to pronounce. B) These compounds are encountered frequently. C) The common names are more widely known. D) all of the above

Q: Molecular oxygen, O2, and ozone, O3, are both examples of A) atoms. B) elements. C) compounds. D) mixtures.

Q: Which statement best describes a compound? A) a material that is made up of a combination of atoms bonded together B) a mixture of more than one element C) a mixture of atoms D) a material that is made up of a single type of atom E) none of the above

Q: How many atoms are in one molecule of Na2SO4? A) 7 B) 2 C) 4 D) 3 E) 24

Q: How many atoms of Oxygen (O) are in H3OClO4? A) 5 B) 2 C) 3 D) 7 E) 1

Q: How many different elements are in the compound C6H12O6? A) 3 B) 6 C) 24 D) All of the elements are the same.

Q: If you have two molecules of TiO2, how many oxygen atoms would you have? A) 4 B) 2 C) 3 D) 6 E) none

Q: If you have one molecule of TiO2, how many molecules of O2 does it contain? A) None, O2 is a different molecule than TiO2. B) One, TiO2 is a mixture of Ti and O2. C) Two, TiO2 is a mixture of Ti and 2 O. D) Three, TiO2 contains three molecules. E) none of the above

Q: Oxygen atoms are used to make water molecules. Does this mean that oxygen, , and water, O, have similar properties? A) Yes, and this explains how fish are able to breathe water. B) Yes, but that their properties are similar is only a coincidence. C) No, but their similar properties are only a coincidence. D) No, compounds are uniquely different from the elements from which they're made.

Q: If you eat metallic sodium or inhale chlorine gas, you stand a strong chance of dying. Let these two elements react with each other, however, and you can safely sprinkle the compound on your popcorn for better taste. What is going on? A) After these two elements react they lose the potential energy to cause harm. B) All elements are inherently dangerous. C) Sodium and chlorine from the elemental form is more concentrated than the sodium and chlorine we get from sodium chloride. D) Sodium chloride has nothing in common with sodium and chlorine.

Q: Which of the following boxes represents a compound? A B C A) only A B) only B C) only C D) both A and C

Q: Which of the following is not a chemical change? A) a rock being crushed to powder B) grass growing C) grape juice turning into wine D) a loaf of bread growing mold E) wood burning to ash

Q: The element silicon has a melting point of 1,410C and a boiling point of 2,355C. It is a weak conductor of electricity, its density is 2.3 grams per cubic centimeter and it easily forms silicon dioxide when exposed to air. Which of the following is a chemical property of silicon? A) its ability to conduct electricity B) its density C) its melting point D) its ability to react with oxygen E) C and D

Q: A skillet is lined with a thin layer of cooking oil followed by a layer of unpopped popcorn kernels. Upon heating the kernels all pop thereby escaping the skillet. Which of the following physical and/or chemical changes occurred? A) The water within each kernel is heated to the point that it would turn into water vapor as the kernels popped (physical change). B) The starches within the kernels are cooked by the high temperatures (chemical change). C) Both A and B occur. D) Physical and chemical changes cannot occur without a real chemical reaction taking place.

Q: In the winter Vermonters make a tasty treat called "sugar on snow" in which they pour boiled-down maple syrup onto a scoop of clean fresh snow. As the syrup hits the snow it forms a delicious taffy. Which of the following changes are involved in the making of sugar on snow? A) Boiling down the maple syrup involves the evaporation of water. B) The syrup warms the snow causing it to melt while the syrup becomes more viscous. C) As the maple syrup is boiled the sugar within the syrup begins to caramelize, which is an example of a chemical change. D) All of the above changes are involved in the making of sugar on snow.

Q: Each night you measure your height just before going to bed. When you arise each morning, you measure your height again and consistently find that you are 1 inch taller than you were the night before but only as tall as you were 24 hours ago! Is what happens to your body in this instance best described as a physical change or a chemical change? A) chemical change because it involves your body B) physical change because it readily reverses C) chemical change because it involves changes in your bone structure D) physical change because water expands as it freezes

Q: Classify the following changes as physical or chemical. Wood burns to ashes; water begins to boil; grass grows; a rock is crushed to powder. A) chemical; physical; chemical; chemical B) chemical; physical; physical; physical C) physical; physical; chemical; physical D) chemical; physical; chemical; physical

Q: Is the following transformation representative of a physical change or a chemical change? A) chemical change because of the formation of elements B) physical change because a new material has been formed C) chemical change because the atoms are connected differently D) physical change because of a change in phase

Q: Based on the information given in the following diagrams, which substance has the lower boiling point: one made from molecule A or one made from molecule B? A) molecule A because it is the first to transform into a liquid B) molecule B because it is first to transform into a liquid C) molecule A because it remains in the gaseous phase D) molecule B because it remains in the gaseous phase

Q: What chemical change occurs when a wax candle burns? A) The wax near the flame melts. B) The molten wax is pulled upwards through the wick. C) The wax within the wick is heated to about 600C. D) The heated wax molecules combine with oxygen molecules.

Q: Oxygen, , is certainly good for you. Does it follow that if small amounts of oxygen are good for you then large amounts of oxygen would be especially good for you? A) Yes. This is the reason patients are given pure (100%) oxygen during medical procedures. B) Yes. Increased oxygenation of the bloodstream is good for you and can increase your life span. C) No. Breathing 100% oxygen for extended periods of time can be damaging to the body. D) No. Large amounts of oxygen will absorb hydrogen from the body and increase the amount of water in the body causing an imbalance in electrolytes.

Q: Is aging primarily an example of a physical or chemical change? A) Aging is an example of a physical change since it involves our physical bodies getting older each day. B) Aging is an example of a chemical change involving the chemical reformation of our biomolecules. C) Aging cannot be classified as either a physical or chemical change. D) None of the above is true.

Q: A sample of iron weighs more after it rusts because A) it has expanded into a greater volume. B) rust contains twice as many iron atoms. C) of the additional oxygen it contains. D) Wrong. Iron actually weighs less after it rusts.

Q: The boiling point of methanol is 65C and the boiling point of ethanol is 78C. Which of the following statements is true? A) At 70C you would have methanol gas and liquid ethanol. B) At 90C you would have methanol and ethanol as solids. C) At 50C you would have methanol and ethanol as gases. D) At 40C the methanol reacts with the ethanol. E) none of the above

Q: Water and ethanol can be separated by heating the ethanol until it boils away from the water. What type of change is this? A) a physical change B) a chemical change C) a molecular change D) a decomposition E) none of the above

Q: A chemical change results in A) new atoms. B) a physical change. C) new materials. D) a new phase.

Q: A chemical change involves the formation or breaking of A) an atom. B) the phase of the material. C) a chemical bond. D) all of the above

Q: Which of the following would be considered a physical property? A) density B) flammability C) corrosion resistance D) reactivity towards acid E) oxygen sensitivity

Q: Which of the following would not be considered a physical property? A) temperature at which a material catches on fire B) color C) conductivity D) hardness E) temperature at which a material melts

Q: Which of the following would be considered a chemical property? A) reactivity towards water B) melting temperature C) boiling temperature D) conductivity E) flexibility

Q: Which of the following would not be considered a chemical property? A) the temperature at which a liquid will boil B) light sensitivity C) whether a metal will rust or not D) whether a material will dissolve in acid or not E) the tendency of a material to explode

Q: Which of the following is an example of a physical change? A) water boiling and being converted into steam B) water being electrolyzed and being converted in hydrogen and oxygen C) iron metal reacting with oxygen to form rust D) a candy bar being digested by a student E) charcoal being converted into ash

Q: Which of the following is an example of a chemical change? A) gasoline being used in the engine of a car producing exhaust B) water freezing into ice crystals C) aftershave or perfume on your skin generating a smell D) a piece of metal expanding when heated, but returning to original size when cooled E) breaking a glass window

Q: The following image describes what type of change? A) a chemical change B) a physical change C) a change in state D) no change E) an elemental change

Q: The following image describes which type of change? A) a physical change B) a chemical change C) an elemental change D) a change in reactivity E) no change

Q: There are about A) 10 different types of atoms. B) 100 different types of atoms. C) a thousand different types of atoms. D) an unlimited number of different types of atoms.

Q: A supercritical fluid least resembles A) a solid. B) a liquid. C) a gas. D) All of the above.

Q: In what phase of matter are the particles no longer moving? A) solid B) liquid C) gas D) none of the above

Q: What is found in between the particles of a gas? A) air B) nothing C) elements D) temperature

Q: How would you describe the size of the following object? a blood cell A) microscopic B) macroscopic C) submicroscopic D) all of the above E) none of the above

Q: How would you describe the volume of the following object? the amount of water in a swimming pool A) microscopic B) macroscopic C) submicroscopic D) all of the above E) none of the above

Q: A TV screen looked at from a distance appears as a smooth continuous flow of images. Up close, however, we see this is an illusion. What really exists are a series of tiny dots (pixels). This is similar to a chemist's view of matter in that A) the fundamental particles of matter can also be seen when looked at closely with a magnifying glass. B) on the submicroscopic level, chemist's find that matter is made of extremely small particles, such as atoms and molecules. C) anything that a chemist can see, touch, hear, smell, or taste is an illusion. D) elements are made up of only three basic types of matter.

Q: The "Responsible Care" program was created by A) academica. B) the government. C) industry. D) non-profit non-governmental organizations.

Q: Chemistry is the study of A) matter. B) transformations of matter. C) only microscopic phenomena. D) only macroscopic phenomena. E) both A and B

Q: Which of the following can be classified as matter? A) water B) sand C) perfume D) ice cream E) all of the above

Q: Which of the following not generally thought of as matter? A) light B) trees C) air D) clouds E) rain

Q: Which of the following would be considered basic research? A) examining why a mouse likes cheddar cheese more than swiss cheese B) studying ways of catching mice safely C) testing the strength of a mouse cage D) examining how quickly a trapdoor closes E) testing a safe, nontoxic mouse glue

Q: An example of basic research is A) the development of new plastics that can be recycled. B) the study of the relationship between the amount of automobile emissions gases in the atmosphere and the decomposition of atmospheric ozone. C) the study of the composition of the atom. D) the design of new batteries for electric cars. E) the study of natural compounds in sea animals to look for new molecules that can be used for medicine.

Q: Which of the following would be considered applied research? A) determining the lightest and strongest metal to be used for an airplane wing B) testing the strength of a piece of metal C) determining the melting temperature of a metal D) examining how susceptible a metal is to bending E) determining how readily a metal corrodes in a wet environment

Q: Of the three sciences, physics, chemistry, and biology, the most complex is A) physics because it involves many mathematical equations. B) chemistry because there are so many possible combinations of atoms. C) biology because it is based upon both the laws of chemistry and physics. D) All three of these sciences are equally complex.

Q: Is chemistry the study of the submicroscopic, the microscopic, or the macroscopic, or all three? A) Submicroscopic because it deals with atoms and molecules, which can't be seen with a microscope. B) Microscopic because it pertains to the formation of crystals. C) Macroscopic because it deals with powders, liquids, and gases that fill beakers and flasks. D) All of the above because most everything is made of atoms and molecules.

Q: What do members of the Chemical Manufacturers Association pledge in the Responsible Care program? A) The members pledge to manufacture utilizing responsible chemical standards. B) The members pledge to manufacture without causing environmental damage. C) The members pledge responsible care for all laboratory test animals. D) The members pledge responsible care by using only USP grade reagents.

Q: Just after an alpha particle leaves the nucleus, would you expect it to speed up? Why? A) No. Once the alpha particle leaves the nucleus it is slowed by the repulsion of the next closest atom's nucleus. B) No. As the alpha particle leaves the nucleus it is slowed by the constant attraction of the electrons surrounding the nucleus. C) Yes. Once the alpha particle leaves the nucleus there are no more forces acting on it and it therefore accelerates. D) Yes. Once the alpha particle leaves the nucleus it accelerates because of mutual electric repulsion with the nucleus from which it escaped.

Q: Why are smaller nuclei such as carbon-14 often radioactive? (carbon-12 is the most common and most stable form of carbon.) A) The attractive force of the nucleons has a limited range. B) The isolated neutron is not stable and will undergo spontaneous transformation into a proton and an electron. C) Hmmm... mysterious are the ways of the force. D) both A and B E) none of the above

Q: The element uranium (U, atomic no. = 92) often has 146 (or more) neutrons but it will still undergo radioactive decay. Which statement might best describe why? A) The attractive force of the nucleons has a limited range. B) The isolated neutron is not stable and will undergo spontaneous transformation into a proton and an electron. C) The force is strong with U, but tainted with the dark side it is. D) both A and B E) none of the above

Q: Why is the combination of two protons and two neutrons stable, but two protons and one neutron is not? A) There are not enough neutrons to overcome the electrical repulsion of the protons. B) There are not enough neutrons to overcome the nuclear repulsion of the protons. C) The nuclear attraction between protons is greater than that between neutrons. D) The electrical repulsion between the two protons is greater in one case than the other. E) none of the above

Q: Which of the following statements best describes the role of neutrons in the nucleus? A) The neutrons stabilize the nucleus by attracting other nucleons. B) The neutrons stabilize the nucleus by forming bonds with other neutrons. C) The neutrons stabilize the nucleus by attracting protons. D) The neutrons stabilize the nucleus by balancing charge. E) The neutrons stabilize the nucleus by adding mass.

Q: Which of the following statements best describes the strong nuclear force? A) The force is very strong but has a very short range. B) The electrical force is stronger than the nuclear force. C) The force is very strong and works over very long distances. D) The strength of the force increases with distance. E) The force has two sides: the light side and the dark side.