Assignment:
Part 1
Choose the BEST answer to each of the following.
1. Which type of radiation from cosmic sources predominates on the inside of a high-flying commercial airplane?
(a) alpha radiation
(b) beta radiation
(c) gamma radiation
(d) none because all three are abundant
2. Is it possible for a hydrogen nucleus to emit an alpha particle?
(a) yes, because alpha particles are the simplest form of radiation
(b) no, because it would require the nuclear fission of hydrogen, which is impossible
(c) yes, but it does not occur very frequently
(d) no, because it does not contain enough nucleons
3. A sample of radioactive material is usually a little warmer than its surroundings because
(a) it efficiently absorbs and releases energy from sunlight.
(b) its atoms are continuously being struck by alpha and beta particles.
(c) it is radioactive.
(d) it emits alpha and beta particles.
4. What evidence supports the contention that the strong nuclear force is stronger than the electric interaction at short internuclear distances?
(a) Protons are able to exist side by side within an atomic nucleus.
(b) Neutrons spontaneously decay into protons and electrons.
(c) Uranium deposits are always slightly warmer than their immediate surroundings.
(d) Radio interference arises adjacent to any radioactive source.
5. When the isotope bismuth-213 emits an alpha particle, what new element results?
(a) lead
(b) platinum
(c) polonium
(d) thallium
6. A certain radioactive element has a half-life of 1 h. If you start with a 1-g sample of the element at noon, how much of this same element will be left at 3:00 PM?
(a) 0.5 g
(b) 0.25 g
(c) 0.125 g
(d) 0.0625 g
7. The isotope cesium-137, which has a half-life of 30 years, is a product of nuclear power plants. How long will it take for this isotope to decay to about one-half of its original amount?
(a) 0 years
(b) 15 years
(c) 30 years
(d) 60 years
(e) 90 years
8. If uranium were to split into 90 pieces of equal size instead of 2, would more energy or less energy be released?
(a) less energy, because of less mass per nucleon
(b) less energy, because of more mass per nucleon
(c) more energy, because of less mass per nucleon
(d) more energy, because of more mass per nucleon
9. Which process would release energy from gold: fission or fusion? From carbon?
(a) gold: fission; carbon: fusion
(b) gold: fusion; carbon: fission
(c) gold: fission; carbon: fission
(d) gold: fusion; carbon: fusion
10. If an iron nucleus split in two, its fission fragments would have
(a) more mass per nucleon.
(b) less mass per nucleon.
(c) the same mass per nucleon.
(d) either more or less mass per nucleon.
Part 2
Choose the BEST answer to each of the following.
1. Chemistry is the study of
(a) matter.
(b) transformations of matter.
(c) only microscopic phenomena.
(d) only macroscopic phenomena.
(e) both a and b.
2. Imagine that you can see individual molecules. You watch a small collection of molecules that are moving around slowly while vibrating and bumping against one another. The slower-moving molecules then start to line up, but as they do so, their vibrations increase. Soon all the molecules are aligned and vibrating about fixed positions. What is happening?
(a) The sample is being cooled and the material is freezing.
(b) The sample is being heated and the material is melting.
(c) The sample is being cooled and the material is condensing.
(d) The sample is being heated and the materal is boiling.
(e) The sample is unchanged.
3. The phase in which atoms and molecules no longer move is the
(a) solid phase.
(b) liquid phase.
(c) gas phase.
(d) none of the above.
4. What chemical change occurs when a wax candle burns?
(a) The wax near the flame melts.
(b) Carbon soot collects above the flame.
(c) The molten wax is pulled upward through the wick.
(d) The heated wax molecules combine with oxygen molecules.
(e) Two of the above are signs of chemical change.
5. 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, which is the first to transform into a liquid
(b) molecule B, which is the first to transform into a liquid
(c) molecule A, which remains in the gaseous phase
(d) molecule B, which remains in the gaseous phase
6. Does the following transformation represent a physical change or a chemical change?
(a) chemical, because of the formation of elements
(b) physical, because a new material has been formed
(c) chemical, because the atoms are connected differently
(d) physical, because of a change in phase
7. Which is an example of a chemical change?
(a) water freezing into ice crystals
(b) aftershave or perfume on your skin generating a smell
(c) a piece of metal expanding when heated, but returning
to its original size when cooled
(d) breaking a glass window
(e) gasoline in the engine of a car producing exhaust
8. If you burn 50 g of wood and produce 10 g of ash, what is the total mass of all the products produced from the burning of this wood?
(a) more than 50 g
(b) 10 g
(c) less than 10 g
(d) 50 g
(e) none of the above
9. If you have one molecule of TiO2, how many molecules of O2 does it contain?
(a) One, TiO2 is a mixture of Ti and O2.
(b) None, O2 is a different molecule than TiO2.
(c) Two, TiO2 is a mixture of Ti and 2 O.
(d) Three, TiO2 contains three molecules.
10. What is the name of the compound CaCl2?
(a) carbon chloride
(b) dichlorocalcium
(c) calc two
(d) dicalcium chloride
(e) calcium chloride
Part 3
Choose the BEST answer to each of the following.
1. An atom loses an electron to another atom. Is this an example of a physical or chemical change?
(a) chemical change involving the formation of ions
(b) physical change involving the formation of ions
(c) chemical change involving the formation of covalent bonds
(d) physical change involving the formation of covalent bonds
2. Aluminum ions carry a 3+ charge, and chloride ions carry a 1- charge. What is the chemical formula for the ionic compound aluminum chloride?
(a) Al3Cl
(b) AlCl3
(c) Al3Cl3
(d) AlCl
3. Which would you expect to have a higher melting point: sodium chloride, NaCl, or aluminum oxide, Al2O3?
(a) aluminum oxide, because it is a larger molecule and has a greater number of molecular interactions
(b) NaCl, because it is a solid at room temperature
(c) aluminum oxide, because of the greater charges of the ions and hence the greater force of attraction between them
(d) aluminum oxide, because of the covalent bonds within the molecule
4. Why are ores so valuable?
(a) They are sources of naturally occurring gold.
(b) Metals can be efficiently extracted from them.
(c) They tend to be found in scenic mountainous regions.
(d) They hold many clues to Earth's natural history.
5. In terms of the periodic table, is there an abrupt or a gradual change between ionic and covalent bonds?
(a) An abrupt change occurs across the metalloids.
(b) Actually, any element of the periodic table can form a covalent bond.
(c) There is a gradual change: the farther apart, the more ionic.
(d) Whether an element forms one or the other depends on nuclear charge and not on the relative positions in the periodic table.
6. A hydrogen atom does not form more than one covalent bond because it
(a) has only one shell of electrons.
(b) has only one electron to share.
(c) loses its valence electron so readily.
(d) has such a strong electronegativity.
7. When nitrogen and fluorine combine to form a molecule, the most likely chemical formula is
(a) N3F.
(b) N2F.
(c) NF4.
(d) NF.
(e) NF3.
8. A substance consisting of which molecule shown below should have a higher boiling point? S"C"O O"C"O
(a) the molecule on the left, SCO, because it comes later in the periodic table
(b) the molecule on the left, SCO, because it is less symmetrical
(c) the molecule on the right, OCO, because it is more symmetrical
(d) the molecule on the right, OCO, because it has more mass
9. The hydrogen bond is a type of
(a) ionic bond.
(b) metallic bond.
(c) covalent bond.
(d) none of the above
10. Iodine, I2, has a higher melting point than fluorine, F2, because its
(a) atoms are larger.
(b) molecules are heavier.
(c) nonpolarity is greater.
(d) atoms have greater electronegativity.