Chem/Phys Content Review
The combustion of methane is given by the reaction: CH4 + 2 O2 --> CO2 + 2 H2O If 20 moles of methane and 20 moles of oxygen are initially present, how many moles of carbon dioxide are produced? A. 1 B. 10 C. 20 D. 30
B. 10 If we have 20 moles of methane, we will need twice as much (or 40 moles) of oxygen to obtain a stoichiometric amount because the ratio of oxygen to methane is 2:1 If we have 20 moles of oxygen, we generate half as much (2:1 ratio) of carbon dioxide. Thus, we will generate only 10 moles of carbon dioxide, making choice B the correct answer.
Which of the following could be the electron configuration of a boron atom in an excited state? A. 1s22s22p1 B. 1s22s12p2 C. 1s22s12p1 D. 1s22s22p2
B. 1s22s12p2 A boron atom contains 5 electrons, so choices "1s22s22p2" and "1s22s12p1" are eliminated immediately, since they account for 6 and 4 electrons, respectively. The configuration in choice "1s22s22p1" is for a boron atom in the ground state, so the answer must be choice "1s22s12p2".
Which of the following appropriately ranks the atoms from smallest to largest atomic radius? A. Ge < Al < P < C B. C < P < Al < Ge C. C < Al < P < Ge D. Ge < P < Al < C
B. C < P < Al < Ge
Which of the following compounds is least likely to be soluble in water? A. NH3 B. CS2 C. CH3OH D. LiF
B. CS2 Since water is a polar molecule that has hydrogen bonds as intermolecular forces, other hydrogen-bonding compounds like NH3 and CH3OH should be very soluble in water (choices A and C are wrong). Since LiF is an ionic compound that dissociates into charged particles in solution, it will need a polar solvent to dissolve (choice D is wrong). CS2, however, is a nonpolar compound and is the least soluble in water, making it the best choice (choice B is correct).
Beta decay is most likely to have what effect on atomic radius? A. Increased atomic radius due to decreased shielding B. Decreased atomic radius due to increased effective nuclear charge C. Decreased atomic radius due to loss of an electron D. Beta decay has no effect on atomic radius.
B. Decreased atomic radius due to increased effective nuclear charge Beta decay involves the conversion of a neutron to a proton (with release of an electron) and an increase in effective nuclear charge. An increase in effective nuclear charge is accompanied by a decrease in atomic radius. Therefore, choice B is correct and choices A and D are incorrect. The loss of the electron in beta decay is from the nucleus, not the surrounding orbitals and is therefore unlikely to cause the decrease in atomic radius, eliminating choice C.
A graduate student estimates the chemical energy in a solution before and after a reaction. The chemical potential energy following the reaction is significantly reduced and the student hypothesizes that the unaccounted energy transitioned to thermal energy. Which of the following laws of thermodynamics best explains this observation? A. Zeroth law B. First law C. Second law D. Third law
B. First law law of conservation of energy boiii
A scientist is experimenting with enzymes found in the human body. Of the following, which would make the most appropriate buffer for such work? A. C6H5COOH (Ka = 6.5 × 10-5) B. HClO (Ka = 3.5 × 10-8) C. HCN (Ka = 4.9 × 10-10) D. H3CNH3+ (Ka = 2.2 ×10-11)
B. HClO (Ka = 3.5 × 10-8) The human body has a pH of 7.4. It is best to choose a buffer whose pKa value is close to the pH that one is trying to maintain. Since HClO has a Ka value of 3.5 × 10-8, we know that its pKa is a little less than 8 (in fact, it's about 7.5).
Which bond is most polar? A. C—Si B. H—Cl C. N—O D. F—F
B. H—Cl F—F bond is nonpolar because there is no difference in electronegativity between the two atoms (eliminate choice D). Since the C—Si and N—O pairs of elements are right next to each other on the table, they are only slightly polar (eliminate choices A and C), while hydrogen and chlorine are far from each other, yielding the most uneven sharing of electrons in the bond.
Rank the following atoms/ions in order of increasing atomic/ionic radius: I.Ne II.Ar III.S2- IV.Cs+ A. I < IV < II < III B. I < II < III < IV C. III < II < I < IV D. IV < I < II < III
B. I < II < III < IV Cesium ion, despite its positive charge, possesses an additional two electron shells than any of the other answer choices and will be largest (eliminating answer choices "I < IV < II < III" and "IV < I < II < III"). Neon, with its large effective nuclear charge and limited number or shells, is the smallest (choice "I < II < III < IV" is correct). Sulfur and argon possess the same number of electrons, but argon has a greater effective nuclear charge which accounts for its smaller size.
Rank the following species by increasing boiling point. I. CH3CHO II. F2 III. CH3OH IV. KBr A. I < II < III < IV B. II < I < III < IV C. III < I < IV < II D. II < I < IV < III
B. II < I < III < IV
The acidity of hydrogen halides increases as one moves down the periodic table. Which of the following properties of halides is most useful in explaining this trend? A. Boiling point B. Ionic radius C. Density D. Atomic weight
B. Ionic radius Moving down the periodic table, the ionic radii of the atoms increase.
Which of the following has the smallest radius? A. S2- B. K+ C. Cl- D. Ar
B. K+
Which of the following is true about the amount of shielding the highest energy electrons of calcium and arsenic experience? A. The electrons of calcium have a greater amount of shielding than the electrons of arsenic. B. The electrons of calcium have a lesser amount of shielding than the electrons of arsenic. C. The electrons of calcium have the same amount of shielding as the electrons of arsenic. D. The amount of shielding between the electrons of calcium and of arsenic can only be determined experimentally.
B. The electrons of calcium have a lesser amount of shielding than the electrons of arsenic. The amount of shielding that the highest energy electrons of an atom feels is determined by the number of filled shells in that atom (inner core electrons), as well as subshells within an energy level (eliminate choice D). Because calcium and arsenic are in the same period (row), they have the same number of inner core electrons. However, the highest energy electrons in arsenic are in the p subshell and are shielded by the electrons in the s subshell. Since the highest energy electrons in calcium are in the s subshell, there is more shielding for arsenic, eliminating choices A and C.
Which of the following ions will align itself parallel to the poles of a magnetic field? A. Ca2+ B. V3+ C. Cr6+ D. Se2-
B. V3+ Any atom or ion that aligns itself parallel to a magnetic field is defined as paramagnetic, and all such species have unpaired electrons in their orbitals. Therefore, eliminate as incorrect any choice that has only completely filled orbital subshells. Ca2+ (Z = 20) has a closed shell noble gas configuration because it is isoelectronic with argon, having 18 e-s (eliminate choice A). V3+ (Z = 23) has 20 e-s, two of which are unpaired in two 3d orbitals since transition metals lose their s electrons first when forming cations (choice B is correct). Both Cr6+ (Z = 24) and Se2- (Z = 34) are also ions with closed shell noble gas configurations with 18 e-s and 36 e-s, respectively. As such, they like Ca2+ will also be diamagnetic with all electrons paired (eliminate choices C and D).
Which type of visible light, red or violet, has the highest energy? A. Violet light, because it has a lower frequency. B. Violet light, because it has a shorter wavelength. C. Red light, because it has a higher frequency. D. Red light, because it has a longer wavelength.
B. Violet light, because it has a shorter wavelength.
Give the electron configuration of a ground state Zn2+ ion. A. [Ar] 4s23d8 B. [Ar] 3d10 C. [Ar] 4s13d9 D. [Ar] 4s23d10
B. [Ar] 3d10
As you move from left to right across the periodic table, the atomic radii of elements in the same period: A. decrease because the amount of shielding increases. B. decrease because effective nuclear charge increases. C. increase because the amount of shielding decreases. D. increase because of increased electron-electron repulsion.
B. decrease because effective nuclear charge increases. As you move left to right across a period, the elements have more protons, giving the atoms increasing effective nuclear charges after the shielding of the inner core electrons are factored in. This change in effective nuclear charge due to proton number plays a more significant role across a period than changes in shielding (choices A and C are wrong). The increased effective nuclear charge means that the valence electrons feel a stronger pull to the nucleus, thus the radius decreases from left to right. Any electron-electron repulsion is more than counteracted by the increased effective nuclear charge, making B a better answer than D.
Under what conditions are gases most soluble? A. high P and high T B. high P and low T C. low P and high T D. low P and low T
B. high P and low T
A spontaneous reaction can be made non-spontaneous if: A. ΔH > 0, ΔS > 0, and the temperature is raised. B. ΔH < 0, ΔS < 0, and the temperature is raised. C. ΔH > 0, ΔS < 0, and the temperature is lowered. D. ΔH < 0, ΔS > 0, and the temperature is lowered.
B. ΔH < 0, ΔS < 0, and the temperature is raised. A negative ΔH and positive ΔS will always be spontaneous at any temperature, while a positive ΔH and negative ΔS will always be non-spontaneous at any temperature (eliminate choices C and D). A positive ΔH and positive ΔS will be non-spontaneous at low temperatures, and will become spontaneous as temperature increases (i.e. increasing the contribution of the entropy term), so choice A can be eliminated. A negative ΔH and negative ΔS will be spontaneous at low temperatures, and will become non-spontaneous as temperature increases, thus making choice B the best answer.
Which one of the following correctly represents the electron configuration of sulfur in an excited state? A. 1s2 2s2 2p6 3s2 3p5 B. 1s2 2s2 2p6 3s2 3p4 4s1 C. 1s2 2s2 2p6 3s2 3p3 4s1 D. 1s2 2s2 2p6 3s2 3p4
C. 1s2 2s2 2p6 3s2 3p3 4s1
Which of the following compounds would exhibit the strongest intermolecular forces? A. CO2 B. CHCl3 C. CH3CO2H D. C6H14
C. CH3CO2H CH3CO2H (acetic acid) possesses both a hydrogen bound to an oxygen and unbound electrons on another oxygen allowing it to form hydrogen bonds. Since hydrogen bonds are the strongest type of intermolecular force, this is the correct answer. CO2 is capable of only weak London dispersion forces given its linear geometry. C6H14 (hexane) is a nonpolar molecule, making it capable of only London dispersion forces as well (choices A and D are incorrect). CHCl3 can form dipole-dipole interactions which are stronger than dispersion forces, but not as strong as hydrogen bonds
Which of the following molecules is polar? A. C2H6 B. CS2 C. CO D. CCl4
C. CO Carbon monoxide has two atoms with a slight difference in electronegativity and so it has a dipole moment. Ethane has only C-C and C-H bonds, neither of which are polar. Without polar bonds the molecule cannot be polar (eliminate choice A). While carbon disulfide and carbon tetrachloride contain polar bonds, they are also symmetrical molecules, so the bond dipoles cancel each other out, leaving nonpolar molecules
Why does the number of electrons not play a role in determining the mass number of an atom? A. The definition of mass number was created before the discovery of the electron. B. Negative charges interfere with any measurement of mass number. C. Electrons have a significantly lower mass compared to protons and neutrons. D. The movement of electrons outside the nucleus interferes with any measurement of mass number.
C. Electrons have a significantly lower mass compared to protons and neutrons. Electrons are excluded from the determination of mass number since they are much less massive (1/1836 AMU) than a proton or neutron (both approximately 1 AMU)
Which variable pair listed below is inversely proportional to each other when all other variables are held constant? A. Pressure and temperature B. Volume and temperature C. Moles of gas and temperature D. Moles of gas and pressure
C. Moles of gas and temperature
A researcher investigates an endothermic reaction found to be non-spontaneous in a temperature-independent manner. Which of the following is the reaction being studied? A. 2 H2O(g) → 2 H2(g) + O2(g) B. CO2(s) → CO2(l) C. N2(g) + 2 O2(g) → 2 NO2(g) D. N2O4(g) → 2 NO2(g)
C. N2(g) + 2 O2(g) → 2 NO2(g)
Which of the following pairs will have the strongest intermolecular forces between them? A. O2 and N2 B. HCl and CHCl3 C. NaCl and NH3 D. H2O and C8H18
C. NaCl and NH3
What is the reactivity, as indicated by the tendency to lose an electron, of sodium compared to potassium? A. This cannot be determined from the information given. B. Potassium has a lower reactivity because potassium has more protons than sodium. C. Potassium has a higher reactivity because the valence electron on potassium is farther from the nucleus. D. Both metals have the same reactivity because the potassium and sodium valence electrons experience the same effective nuclear charge.
C. Potassium has a higher reactivity because the valence electron on potassium is farther from the nucleus. The reactivity of sodium compared to potassium is that potassium has a higher reactivity because the valence electron on potassium is farther from the nucleus. Reactivity of metallic elements increases down a column of the periodic table. This increase in reactivity corresponds with increased shielding from inner electron shells, increased atomic radius, and decreased ionization energy. Thus, electrons are easier to remove in potassium versus sodium.
Which of the following will release the most energy with the addition of an electron? A. Al B. Ga C. Si D. Ge
C. Si
Which of the following elements would be expected to exhibit the greatest ionization energy? A. Calcium B. Potassium C. Titanium D. Scandium
C. Titanium
Which of the following represents the ground state electron configuration of a Co(III) ion? A. [Ar] 4s2 3d4 B. [Ar] 4s2 3d10 C. [Ar] 3d6 D. [Ar] 4s1 3d5
C. [Ar] 3d6
A sample of excited hydrogen atoms emits a light spectrum of specific, characteristic wavelengths. The light spectrum is a result of: A. energy released as H atoms form H2 molecules. B. the light wavelengths which are not absorbed by valence electrons when white light is passed through the sample. C. excited electrons dropping to lower energy levels. D. particles being emitted as the hydrogen nuclei decay.
C. excited electrons dropping to lower energy levels.
How would you increase the solubility of sugar in water? A. increase P B. decrease P C. increase T D. decrease T
C. increase T
Which of the following is not a possible electron configuration for a helium atom? A. 2s2 B. 1s2 C. 1s1 2s1 D. 1s1 2d1
D. 1s1 2d1
Which of the following ions has the largest ionization energy? A. Sr+ B. Ca+ C. Mg+ D. Be+
D. Be+ The ionization energy periodic trend is opposite the trend for atomic radius. Atoms and ions with valence electrons close to the nucleus require more energy to remove them than atoms/ions with valence electrons farther from the nucleus. Since these ions are in the same group on the periodic table, the smallest one (Be) will have the greatest ionization energy.
Which of the following molecules has the greatest boiling point? A. CH3CH2CH2CH3 B. CH3CH2OH C. CH3CHO D. CH3CO2H
D. CH3CO2H
In electrochemistry, which of the following best demonstrates the first law of thermodynamics? A. A galvanic cell proceeding spontaneously B. The overall increase in entropy observed following a reaction C. The chemical reaction proceeding to a more probable state D. Conversion of equal quantities of chemical energy into electrical energy
D. Conversion of equal quantities of chemical energy into electrical energy
Which of the following ions is paramagnetic? A. F- B. Na+ C. Sr2+ D. Cu2+
D. Cu2+
In the formation of a bond, what dictates the distance between the two atoms? A. Distance with maximal electron cloud overlap B. Distance with minimal electron cloud overlap C. Distance at which maximal potential energy is obtained D. Distance at which attractive and repulsive forces are equal
D. Distance at which attractive and repulsive forces are equal
Which of the following would have the highest energy? A. Radio waves, because they have longer wavelengths than gamma rays B. Radio waves, because they have higher frequencies than gamma rays C. Gamma rays, because they have longer wavelengths than radio waves D. Gamma rays, because they have higher frequencies than radio waves
D. Gamma rays, because they have higher frequencies than radio waves Gamma rays have the highest energy in the electromagnetic spectrum (eliminate A and B). High energy is synonymous with short wavelength and high frequency because E = hf and f = c/λ, making choice D the correct answer.
Given the same number of moles, which of the following solids will have the lowest melting point? A. SiO2 B. Cu C. NaI D. H2Se
D. H2Se Hydrogen selenide is a molecular solid. Its intermolecular forces consist of dipole-dipole interactions. Though a relatively strong intermolecular force, they are much weaker than the covalent bonds between the atoms in a network solid (choice A), the covalent bonds between the atoms in a metallic solid (choice B), and the ionic forces between the ions in an ionic solid (choice C). Thus, the weaker intermolecular forces will allow hydrogen selenide to melt more easily than the others.
Which of the following species has/have a trigonal planar shape? I. PF3 II. CO32- III. BCl3 A. I only B. III only C. I and III only D. II and III only
D. II and III only PF3 has four electron groups around the central phosphorus (three single bonds to fluorine and a lone electron pair). It therefore has a trigonal pyramidal shape (eliminate choices A and C). Based on the remaining choices, BCl3 must be trigonal planar; it has three electron groups surrounding the central boron (three single bonds to chlorine). The carbonate ion (CO32-) has three electron groups around the central carbon (two single bonds to oxygen and one double bond to oxygen), making it trigonal planar as well
Which of the following is true of ionization energy? A. It increases with period, and the second ionization energy is greater than the first. B. It decreases with period, and the first ionization energy is greater than the second. C. It increases with period, and the first ionization energy is greater than the second. D. It decreases with period, and the second ionization energy is greater than the first.
D. It decreases with period, and the second ionization energy is greater than the first.
Which of the following is true of an electron in an excited state? A. It has absorbed a photon, and its energy has decreased. B. It has emitted a photon, and its energy has increased. C. It has emitted a photon, and its energy has decreased. D. It has absorbed a photon, and its energy has increased.
D. It has absorbed a photon, and its energy has increased.
When an excited electron in a hydrogen atom falls from the n = 3 to the n = 2 level, a photon of red light is emitted from the atom. Compared to the red photon, what would be true about the electromagnetic radiation emitted if an electron were to fall from n = 4 to n = 3? A. It would have a larger energy and a greater frequency B. It would have a larger energy and a shorter wavelength C. It would have a smaller energy and a greater frequency D. It would have a smaller energy and a longer wavelength
D. It would have a smaller energy and a longer wavelength
Fe(CO)6Cl dissociates into two species, both charged, when dissolved in water. Which is the most likely expression for the dissociation constant (Ksp)? A. Ksp = [Fe+][CO]6[Cl−] B. Ksp = [Fe+][Cl−] C. Ksp = [Fe(CO)3+][Cl(CO)3−] D. Ksp = [Fe(CO)6+][Cl−]
D. Ksp = [Fe(CO)6+][Cl−] Fe(CO)6Cl is a complex salt. Since CO is a neutral ligand, dissociation of one CO will not result in two ionic particles. Therefore, the dissociation must be Fe(CO)6Cl → Fe(CO)6+ + Cl−.
A researcher experimentally determines the atomic mass of an iron sample to be 55.1 amu. Which of the following most likely explains this result? A. The sample has undergone beta decay. B. Part of the sample has been reduced. C. The sample has tin contamination. D. Part of the sample has been oxidized to Fe2O3.
D. Part of the sample has been oxidized to Fe2O3. Atomic mass values listed on the periodic table are weighted averages of the naturally occurring isotopes for each element. 55.1 amu is lower than expected. Fe is metallic and is much more likely to be oxidized than reduced. Beta decay (β-) results in the conversion of a proton to a neutron and an emitted beta particle. Atomic mass does not change significantly in beta decay. Contamination with tin, which is significantly heavier than iron, would yield a higher than expected atomic mass. This leaves the correct answer primarily by process of elimination.
Which of the following is the most stable ionization state for Sn? A. Sn+1 B. Sn+3 C. Sn+4 D. Sn+2
D. Sn+2 Sn+2 is the most stable ionization state for Sn. When Sn loses two electrons, the resulting configuration has a full and stable 4d10 subshell, making Sn2+ the most stable ionization state.
Does a small atomic radius correspond to a high ionization energy? A. No, because the smaller space enhances electron-electron collisions, thus making it easier to remove these electrons. B. No, because the large concentration of negative charge in a smaller space causes increased repulsion, thus making it easier to remove these electrons. C. Yes, because atoms in lower periods exhibit an enhanced strong force on electrons. D. Yes, because the shorter distance between the positive nucleus and the negative electron enhances electrostatic attraction, and thus makes it difficult for these electrons to be removed.
D. Yes, because the shorter distance between the positive nucleus and the negative electron enhances electrostatic attraction, and thus makes it difficult for these electrons to be removed.
Two excited state Bohr atoms experience electron transitions, the first atom E3 to E2, and the second atom from E2 to E1. The electron in the first atom loses: A. a larger energy, thus emitting a photon with a longer wavelength. B. a larger energy, thus emitting a photon with a shorter wavelength. C. a smaller energy, thus emitting a photon with a shorter wavelength. D. a smaller energy, thus emitting a photon with a longer wavelength.
D. a smaller energy, thus emitting a photon with a longer wavelength. There is an inverse relationship between energy and wavelength. Therefore, a larger energy loss is associated with a photon with a shorter wavelength and vice versa
Compared to the atomic radius of S, the atomic radius of Al is: A. smaller, due to decreased nuclear charge. B. smaller, due to increased nuclear charge. C. larger, due to increased nuclear charge. D. larger, due to decreased nuclear charge.
D. larger, due to decreased nuclear charge. Moving left to right across a period, nuclear charge increases due to increasing atomic number (number of protons). As the positive nuclear charge increases, effective nuclear charge increases and electrons are pulled closer to the nucleus, resulting in a decreased atomic radius. Aluminum is therefore larger than sulfur.
What is the hybridation of the central atom in PCl3? A. p B. sp C. sp2 D. sp3
D. sp3
Which of the following electron transitions (between energy levels, labeled by n) could account for the emission of photons of red, yellow, and blue light from a pure noble gas? A.n = 4 to n = 1, n = 4 to n = 2, and n = 4 to n = 3, respectively B.n = 1 to n = 0, n = 2 to n = 1, and n = 3 to n = 2, respectively C.n = 2 to n = 1, n = 3 to n = 2, and n = 4 to n = 3, respectively D.n = 4 to n = 3, n = 3 to n = 2, and n = 2 to n = 1, respectively
D.n = 4 to n = 3, n = 3 to n = 2, and n = 2 to n = 1, respectively The energy of the photons satisfy red < yellow < blue. Therefore, the energy difference between the energy levels that produce these photons must follow the same order. Since the spacing between energy levels decreases with increasing n, then n = 4 to n = 3, n = 3 to n = 2, and n = 2 to n = 1 is best.
Given the enthalpies of formation for NO and NO2 are 90 kJ/mol and 33 kJ/mol, respectively, what is the reaction enthalpy for 2 NO(g) + O2(g) ? 2 NO2(g)? A. -114 kJ/mol B. -57 kJ/mol C. -24 kJ/mol D. Inadequate information provided to answer the question
A. -114 kJ/mol The reaction enthalpy can be calculated by taking the sum of the enthalpies of formation of the products and subtracting from it the sum of the enthalpies of formation of the reactants after multiplying each by their stoichiometric coefficients. Thus we find that the reaction enthalpy is (2 × 33 kJ/mol) - (2 × 90 kJ/mol) = -114 kJ/mol (choice A is correct). Note that we define the enthalpy of formation of elements in their standard state as zero.`
Given the following enthalpies of formation, what is the reaction enthalpy for C3H4(g) + 4 O2(g) → 3 CO2(g) + 2 H2O(l)? ΔH°f for C3H4(g) 185 kJ/mol ΔH°f for CO2(g) -286 kJ/mol ΔH°f for H2O(l) -394 kJ/mol A. -1831 kJ/mol B. -1461 kJ/mol C. -495 kJ/mol D. 865 kJ/mol
A. -1831 kJ/mol The reaction enthalpy can be calculated by taking the sum of the enthalpies of formation of the products and subtracting from it the sum of the enthalpies of formation of the reactants after multiplying each by their stoichiometric coefficients. The enthalpy of formation for elements in their standard state is defined as zero (hence we will not need it for our solution). ( 3*-286 + 2* -394) - 185
Given the reaction below: 2 C2H4 + O2 → 2 C2H4O how many moles of C2H4 remain if 75 moles of C2H4 and 40 moles of O2 were initially present? A. 0 B. 5 C. 35 D. 40
A. 0 If we have 75 moles of methane, we will need half as much (or 32.5 moles) of O2 to obtain a stoichiometric amount because the ratio of O2 to C2H4 is 1:2. However, the problem statement says that we have 40 moles of O2 present, indicating that we have an excess amount. This means that C2H4 is the limiting reactant. Conversely, had we chosen to start with O2, the reasoning is slightly different. If we have 40 moles of oxygen, we will need twice as much (or 80 moles) of C2H4 to obtain a stoichiometric amount, because the ratio of C2H4 to O2 is 2:1.
Which of the following atoms/ions has the greatest radius? A. Br- B. Kr C. Rb+ D. Sr2+
A. Br- All of these atoms and ions are isoelectronic and therefore have the same amount of electron-electron repulsion. Br- has the fewest number of protons, so its electrons feel the least attractive force, making it largest in size.
Which of the following does not have a closed valence shell? A. Cl B. Br- C. Ti4+ D. Kr
A. Cl Chlorine does not have a completely filled p subshell but has an s2p5 electron configuration. The other options have noble gas configurations, giving them the full complement of electrons in their s and p subshells. Br- is isoelectronic with Kr (eliminate choices B and D) and Ti4+ is isoelectronic with Ar (eliminate choice C)
Rank the following elements by increasing atomic radius: N, Ba, F, Te. A. F < N < Te < Ba B. F < N < Ba < Te C. Ba < Te < N < F D. N < F < Te < Ba
A. F < N < Te < Ba
In organic solution, F- deprotonates dissolved HCl. Which of the following explains this observation? A. F- has a smaller radius than Cl-. B. F- is a stronger acid than Cl-. C. F- has a greater electronegativity than Cl-. D. F- has a lower ionization energy than Cl-.
A. F- has a smaller radius than Cl-. F- has a smaller radius than does Cl-, it is less stable with excess charge, and therefore a better Bronsted base. It outcompetes Cl- for the proton.
Which pair of liquids below will be immiscible? A. H2O and CCl4 B. CH3OH and CH3CH2OH C. CH3CH2CH2CH2CH3 and CH3CH2CH2CH2Br D. CCl4 and C6H6
A. H2O and CCl4 The solvent pair that is immiscible will be made of a polar and a nonpolar compound based on the rule of thumb that "like dissolves like." Therefore, compounds that have very different intermolecular forces are least likely to dissolve in each other, and will separate into two layers.
The first three electron energy levels of a hydrogen atom are given as: E1 = -13.6 eV E2 = -3.4 eV E2 = -3.4 eV If an electron is in the E2 level, which of the following will occur spontaneously? A. The electron transitions to E1, and a photon of 10.2 eV is emitted. B. The electron transitions to E3, and a photon of 1.9 eV is emitted. C. The electron transitions to E1, and a photon of 10.2 eV is absorbed. D. The electron transitions to E3, and a photon of 1.9 eV is absorbed.
A. The electron transitions to E1, and a photon of 10.2 eV is emitted.
The reactivity of alkali metals follows the trend Cs > Rb > K > Na > Li. Which of the following is the best explanation for this trend? A. The ionization energy increases from Cs to Li. B. The electron affinity increases from Li to Cs. C. The electronegativity decreases from Cs to Li. D. The atomic size decreases from Li to Cs.
A. The ionization energy increases from Cs to Li.
If an atom's atomic number equals its atomic weight, which of the following would be true? A. The number of protons equals the number of electrons. B. The number of neutrons equals the number of protons. C. The number of neutrons equals the number of electrons. D. The number of protons is less than the number of neutrons.
A. The number of protons equals the number of electrons. The only scenario in which this can occur is if the atom does not contain any neutrons. Thus, for a neutral atom, the number of protons must equal the number of electrons
Which of the following is the correct electron configuration for the iron ions present in rust, Fe2O3? A. [Ar] 3d5 B. [Ar] 4s23d3 C. [Ar] 4s23d4 D. [Ar] 3d6
A. [Ar] 3d5 Oxygen will always have a -2 charge in an ionic compound, so in order to make the formula neutral, each of the two iron ions will be Fe3+. The electron configuration for a neutral iron atom is [Ar] 4s23d6, and three electrons must be removed to yield Fe3+.
Compared to carbon, nitrogen has a: A. greater ionization energy and more negative electron affinity. B. smaller ionization energy and more positive electron affinity. C. smaller ionization energy and more negative electron affinity. D. greater ionization energy and more positive electron affinity.
A. greater ionization energy and more negative electron affinity.
The outermost shell of electrons in the noble gases (with the exception of helium) have which of the following electron configurations? A. ns2np6 B.ns2np4 C.ns2np2 D.ns2np8
A. ns2np6
Which of the following is NOT an assumption of the Kinetic Molecular Theory? A.Gas particles have a small, yet finite volume. B. The average kinetic energy of the gas is directly related to the temperature. C. Collisions of gas particles with each other and the walls of the container are elastic. D. The attraction of gas particles to themselves is assumed to be negligible.
A.Gas particles have a small, yet finite volume.
When French fries are cooling on an aluminum sheet, the sheet cools off faster than the fries. This is because: A.the specific heat of aluminum is less than the specific heat of water in the fries. B.the heat of vaporization for aluminum is greater than that of the water in the fries. C. the specific heat of aluminum is greater than the specific heat of water in the fries. D. the heat of vaporization for aluminum is less than that of the water in the fries.
A.the specific heat of aluminum is less than the specific heat of water in the fries.
