A cat strolls across your backyard.An hour later, a dog with its nose to the ground follows the trail of the cat. Explain what is going on from a molecular point of view
C) The dog is smelling molecules from the cat
Does it makes sense to say that a textbook is about 99.9% empty space?
C) Yes. A textbook like all material things is made up of atoms, which are considered to be 99.9% empty space.
Which of the following statements best describes an element?
A) A material consisting of only one type of atom.
Which of the following statements does not describe a proton?
A) It orbits around the nucleus of an atom.
Which of the following does not describe a neutron?
A) It has a positive charge equivalent but opposite of an electrons
Which of the following statement describes an isotope?
A) Element with the same number of protons but a different number of neutrons.
You could swallow a capsule of germanium, Ge ( atomic # 32) without significant ill effects. If a proton were added to each germanium nucleus, however, you would not want to swallow the capsule because germanium would
A) Become arsenic
What is the difference between radiation an electromagnetic radiation?
A) Radiation is from decay of nuclei while electromagnetic radiation is any form of light.
Rank the following by the relative amounts of energy, from most energetic to least.
A) Cosmic rays, Blue light, red light and radio waves
How can a hydrogen atom, which has only one electron, have so many spectral lines?
C) One electron can be boosted to many different energy levels.
Suppose that a certain atom possesses only 4 distinct energy levels. Assuming that all transitions between levels is possible, how many spectral lines will this atom exhibit?
Which of the following is a property of light?
D) all of above, Its is a wave, particle and its energy comes in packets of uniform size.
What is the main tenet of Planks quantum hypothesis?
A) Energy comes in discrete packets of a certain minimum size.
Which of the following statements about electrons is true?
E) all of above, Electrons have a negative charge, electrons are particles, electrons behave like waves and electrons in atoms can be excited by light energy.
What property of an electron makes it possible to use electron microscopes?
B) They have shorter wavelengths than visible light.
It is relatively easy to pull an electron away from a potassium atom (K, atomic # 19), but very difficult to remove a second one because
C) Of a much greater nuclear charge that it experiences.
You are given 3 radioactive samples ( a, b and y) and can only dispose of one. The other 2 you must keep, 1 in your hand, the other in your pocket. How would you minimize your exposure?
A) Keep a in hand,keep b in pocket and dispose of y.
Which of the following statements best describes the strong nuclear force?
A) The force is very strong but has a very short range.
Which of the following statements best describes the role of neutrons in the nucleus?
C) The neutrons stabilize the nucleus by attracting protons.
Which of the following nuclear equations correctly describes alpha emission?
A) 238/92 U- 234/90 Th + 4/2He
How come animals carbon -14 levels do not start to decrease until it dies?
A) Because it constantly replenishes its carbon-14 supply by eating plants with carbon-14 in them.
The half-life of carbon-14 is 5,730 yrs. A sample is found to have 1/8 the original amount of carbon-14 in it. How old is the sample?
D) 17,200 yrs
Why is carbon-14 dating not accurate for estimating the age of materials more than 50, 000 yrs old?
B) The concentration of carbon-14 in a body after 50,000 yrs old is too low.
Which of the following statements about fission is true?
A) The amount of energy released in the fission of large nuclei is very large.
Which of the following statements about chain reactions is true?
A) The key requirement for a chain reaction is that more neutrons are produced than are absorbed.
What does Einsteins energy equation say about the energy that is derived from nuclear fission reactions?
A) The energy released is due to the missing mass of the products compared to the mass of the starting materials.
Which of the following statements re: a nucleon is true in regards to nuclear reactions?
A) A nucleon inside a nucleus has a lower mass than a nucleon outside a nucleus.
To predict the approximate energy release of either a fission or fusion reaction, explain how physicist uses a table of nuclear masses and the equation E = mc2.
B) Find the change in mass and multiply by the speed of light squared
What is the main technical difficulty in dealing with fusion reactions?
A) The amount of energy needed to overcome the electrical repulsion of the reactants is extremely high.
Which of the following statements about fusion is the most accurate?
A) The mass of products is less than the mass of reactants
Is chemistry the study of the submicroscopic, the microscopic, or the macroscopic, or all three?
D) All 3, because most everything is made of atoms and molecules.
Which of the following can be classified as matter?
E) All of the above, water, sand , perfume and ice cream
Which of the following best describes a gas?
A) The molecules are moving quickly and are widely spaced.
Using the above images illustrating identical volumes of different materials, which has the highest density?
A) sorry no image avail ! :) if i knew how to put those in u wouldnt even need to go to school!
The phase in which atoms and molecules no longer move is
D) None of the above, which were, solid phase, liquid phase or gas phase
Theres a diagram again describing phase of water relative to temp and pressure.
B) Yes,water can be made to sublime. this occurs at D point of diagram, which u cant see!
Is the following transformation representative of a physical change or a chemical change?
C) Chemical change because the atoms are connected differently.
Which statement best describes a compound?
A) A material that is made of a combo of atoms bonded together.
Oxygen atoms are used to make water molecules. Does this mean that oxygen, O2, and water, H20, have similar properties?
D) No. compounds are uniquely different from the elements from which there made.
The systematic names for water , ammonia, and methane are dihydrogen monoxide, H20: trihydrogen nitride, NH3, and tetrahydrogen carbide, CH4. Why do most people, including chemists, prefer to use the common names of these compounds?
D) The common names are more widely known.
Which of the following is the correct electron dot structure for chlorine ( atomic # 17) ? NO IMAGE AVAIL
What is 1 role of unpaired valence electrons?
A) They take part in the formation of different type of bonds
The valence electron of sodium atom does not sense the full +11 0f the sodium nucleus. Why not?
B) There are 2 inner shells of electrons containing ten electrons shielding the sodium nucleus from sensing it.
Which of the following would be an ion with a double positive charge?
C) An Mg atom that loses 2 electrons.
Which of the following best describes ionic bonding?
C) 1 atom giving up some of its electrons to another atom.
How many chloride ions (C1-1) are needed to balance the positive charge of a barium ion (Ba+2) ?
Barium ions carry a +2 charge, and nitrogen ions carry 3- charge. What would be the chemical formula for the ionic compound barium nitride?
What property of metal atoms account for many of the observed bulk phenomena seen in metal samples?
A) Metal atoms easily lose 1 or more outer electrons
There is more gold in 1 Km3 of the ocean than the amount of gold mined in all of recorded history. How come we do not mine the oceans?
D) all of the above, too dilute to seperate, too much energy and it would cost too much.
What is the main difference between an ionic and a covalent bond?
A) One is the sharing of a pair of electrons, the other is the transfer of at least 1 electron.
A hydrogen atom does not form more than 1 covalent bond because it...
B) It has only one electron to share
In terms of the periodic table, is there an abrupt or gradual change between ionic and covalent bonds?
C) There is gradual change: the farther apart, the more ionic.
Which of the following is the weakest form of interatomic attraction?
E) An induced dipole-induced dipole interaction
If ionic bond is stronger than a dipole-dipole interaction, how can water dissolve an ionic compound?
A) The ion-dipole interactions of a bunch of water molecules gang up on the strong ionic bond and pull it into the solution.
What is a hydrogen bond?
A) a special type of dipole-diploe attraction involving hydrogen bound to a highly electronegative atom.
What is the difference between a compound and a mixture?
A) A mixture can be physically separated into its components; a compound can not be physically separated into its components.
Each circle represents an atom. Which box x contains element, a mixture, a compound?
C) Element A, C;compound : A,B; mixture: A
Half-frozen fruit punch is always sweeter than the same fruit punch completely melted because...
B) Crystallization is a purifying process
Many dry cereals are fortified with iron, which is added to the cereal in the form of small iron particles. How might these particles be separated from the cereal?
C) Collect iron fillings with a magnet
What do chicken noodle soup and garden soil have in common?
A) They are both examples of heterogeneous mixtures.
How does a suspension differ from a solution?
C) Although a solution and solution are both homogenous mixtures, only the components of a suspension will separate by spinning the mixture in a centrifuge.
Red-colored Kool-aid crystals are added to a still glass of hot water. The same amount of crystals are added to a second glass filled with the same amount of cold water. With no stirring which of the following would occur?
C) The glass of hot water will reach a uniform red color first since the higher kinetic energy provides for faster moving molecules to more quickly distribute the dye.
Which of the following describes the term concentration?
B) It is the amount of the solute in a given amount of solution.
Which of the following solutions is the most concentrated?
D) 1 liter of water with 10 grams of sugar
How are interatomic forces and solubility related?
D) Solubility is the measure of how weak the intermolecular forces in the solute are.
Which solute graphed above has solubility in water that does not markedly increase with increasing temp?
Why might a solvent like turpentine be better for removing grease and grime than water ?
E) All of the above
Which of the following might best describe the product obtained from soap and hard water, i.e. soap scum?
Why might sodium carbonate be added to hard water to aid in cleaning?
A) The hard ions in the water are more attracted to the carbonate ions -2 charge.
Why might softened water not be good for some one who is trying to reduce their dietary sodium ion intake?
B) Water softeners work by replacing the calcium and magnesium ions of the water with sodium ions, softened water contains increased levels of sodium ions.
What is the purpose of adding aluminum salts and a base to water during water treatment?
A) The 2 together gel and trap dirt and bacteria.
What is the purpose of allowing water to cascade or bubble in a fountain during the purification process?
D ALL OF ABOVE
Might reverse osmosis be used obtain fresh water from a sugar-water solution?
B) Yes, reverse osmosis can be applied to any aqueous solution for the generation of fresh water?
Why secondary treatment often needed for sewage?
A) The dissolved organics are to high and lead to bacterial growth.
What is the easiest way to eliminate organic components?
A) Aerate the solution and let bacteria consume the organics
You heat 20 grams of metal in an open container and after the experiment you are left with 35 grams of a powdery substance. Which statement best explains what happened?
A) The metal reacted with some air or something else we did not originally measure.
Which has more atoms : a 1-gram sample of carbon -12 or a 1-gram sample of carbon -13?
B) A 1-gram sample of carbon -12
How many oxygen molecules are needed to make 10 carbon dioxide molecules according to the following balanced chemical equation?
How is Avogadros # related to the numbers of the periodic table?
A) The atomic mass listed is the mass of Avogadros numbers worth of atoms.
Why might increasing the concentration of a set of reactants increase the rate of reaction?
A) You have increased the chances that any reactant molecules will collide and react.
Why might increasing the temp alter the rate of a chemical reaction?
B) The molecules are less reactive at higher temps.
A refridge delays the spoilage of food by...
B) Slowing down the rate of chemical reactions within microorganisms.
Carefully examine the following reaction sequence for the catalytic formation of ozone, 03, from molecular oxygen, 02. Which chemical compound is behaving as the catalyst?
A) Nitrogen monoxide, NO
Many people here about atmospheric ozone depletion and wonder why we don't simply replace that which has been destroyed. Knowing about CFC'S and how catalysts work, explain how this would not be a lasting solution.
D) all of the above
Given that the energy profiles have the same scale, which of the reactions is the most exothermic?
Given that the bond energy of N2 is 946 kJ/ mole, the bond energy of 02 is 498 kJ/mole and the NO bond energy is 631 kJ/mole, how much energy is required to react 1 mole of nitrogen molecules according to the following reaction?
A) 182 kJ
Are the chemical reactions that take place in a disposable battery exothermic or endothermic? Is the reaction going on in a rechargeable battery while it is recharging exothermic or endothermic?
B) An operating disposable battery is driven by exothermic reaction, while a recharging rechargeable battery is driven by endothermic reactions.
What does a negative entropy tell us?
A) It tell us that the reaction does not proceed without help.
What role does entropy play?
D) The entropy change determines whether the reaction will occur spontaneously or not.
Wild plants grow all by themselves yet the molecules of the growing plant have less entropy than the materials used to make the plant. How is it possible for there to be this decrease in entropy for a process that occurs all by itself?
C) Wild plants don't grow all by themselves. When we consider the entire system, including the sun, we find an overall increase in entropy.