AP Chem Semester 1 Review

Which of the following diagrams best depicts an alloy of Ni and B?

A

On the basis of the information above, which of the following arranges the binary compounds in order of increasing bond polarity? A) CH4 < SiCl4 < SF4 B) CH4 < SF4 < SiCl4 C) SF4 < CH4 < SiCl4 D) SiCl4 < SF4 < CH4

A) CH4 < SiCl4 < SF4

Fe3+(aq) + KSCN(s) → FeSCN2+(aq) + K+(aq) Gases generated in a chemical reaction are sometimes collected by the displacement of water, as shown above. Which of the following gases can be quantitatively collected by this method? A) H2 B) CO2 C) HCl D) SO2 E) NH3

A) H2

The mass percent of carbon in pure glucose, C6H12O6, is 40.0 percent. A chemist analyzes an impure sample of glucose and determines that the mass percent of carbon is 38.2 percent. Which of the following impurities could account for the low mass percent of carbon in the sample? A) Water, H2O B) Ribose, C5H10O5 C) Fructose, C6H12O6, an isomer of glucose D) Sucrose, C12H22O11

A) Water, H2O

The average kinetic energy of the gas molecules is A) greatest in container A B) greatest in container B C) greatest in container C D) the same in all three containers

A) greatest in container A

The first five ionization energies of a second-period element are listed in the table above. Which of the following correctly identifies the element and best explains the data in the table? A) B, because it has five core electrons B) B, because it has three valence electrons C) N, because it has five valence electrons D) N, because it has three electrons in the p sublevel

B) B, because it has three valence electrons

Atoms of Mg combine with atoms of F to form a compound. Atoms of which of the following elements combine with atoms of F in the same ratio? A) Li B) Ba C) Al D) Cl E) Ne

B) Ba

A 23.0 g sample of a compound contains 12.0 g of C, 3.0 g of H, and 8.0 g of O. Which of the following is the empirical formula of the compound? A) CH3O B) C2H6O C) C3H9O2 D) C4H12O2

B) C2H6O

The figure above shows that in solid hydrogen fluoride there are two different distances between H atoms and F atoms. Which of the following best accounts for the two different distances? A) Accommodation of the necessary bond angles in the formation of the solid B) Difference in strength between covalent bonds and intermolecular attractions C) Different isotopes of fluorine present in the samples D) Uneven repulsions among nonbonding electron pairs

B) Difference in strength between covalent bonds and intermolecular attractions

Which of the following best helps to account for the fact that the F- ion is smaller than the O2- ion? A) F- has a larger nuclear mass than O2- has. B) F- has a larger nuclear charge than O2- has. C) F- has more electrons than O2- has. D) F- is more electronegative than O2- is. E) F- is more polarizable than O2- is.

B) F- has a larger nuclear charge than O2- has.

According to the information in the table above, a 1.00 g sample of which of the following contains the greatest mass of oxygen? A) Na2O B) MgO C) K2O D) CaO

B) MgO

The effective nuclear charge experienced by the outermost electron of Na is different than the effective nuclear charge experienced by the outermost electron of Ne. This difference best accounts for which of the following? A) Na has a greater density at standard conditions than Ne. B) Na has a lower first ionization energy than Ne. C) Na has a higher melting point than Ne. D) Na has a higher neutron-to-proton ratio than Ne. E) Na has fewer naturally occurring isotopes than Ne.

B) Na has a lower first ionization energy than Ne.

A sample containing atoms of C and F was analyzed using x-ray photoelectron spectroscopy. The portion of the spectrum showing the 1s peaks for atoms of the two elements is shown above. Which of the following correctly identifies the 1s peak for the F atoms and provides an appropriate explanation? A) Peak X, because F has a smaller first ionization energy than C has. B) Peak X, because F has a greater nuclear charge than C has. C) Peak Y, because F is more electronegative than C is. D) Peak Y, because F has a smaller atomic radius than C has.

B) Peak X, because F has a greater nuclear charge than C has.

The reaction between NO(g) and O2(g) to produce NO2(g) in a rigid reaction vessel is represented in the diagram above. The pressure inside the container is recorded using a pressure gauge. Which of the following statements correctly predicts the change in pressure as the reaction goes to completion at constant temperature, and provides the correct explanation? A) The pressure will increase because the product molecules have a greater mass than either of the reactant molecules. B) The pressure will decrease because there are fewer molecules of product than of reactants. C) The pressure will decrease because the product molecules have a lower average speed than the reactant molecules. D) The pressure will not change because the total mass of the product molecules is the same as the total mass of the reactant molecules.

B) The pressure will decrease because there are fewer molecules of product than of reactants.

Which flask contains the sample with the greatest density? A B C D E

C

A 2 L sample of N2(g) and a 1 L sample of Ar(g), each originally at 1 atm and 0°C, are combined in a 1 L tank. If the temperature is held constant, what is the total pressure of the gases in the tank? A) 1 atm B) 2 atm C) 3 atm D) 4 atm E) 5 atm

C) 3 atm

If the pressure of each gas is increased at constant temperature until condensation occurs, which gas will condense at the lowest pressure? A) Methane B) Ethane C) Butane D) All the gases will condense at the same pressure.

C) Butane

Complete combustion of a sample of a hydrocarbon in excess oxygen produces equimolar quantities of carbon dioxide and water. Which of the following could be the molecular formula of the compound? A) C2H2 B) C2H6 C) C4H8 D) C6H6

C) C4H8

Based on the data in the table above, which of the following liquid substances has the weakest intermolecular forces? A) C6H6 (l) B) C2H5OH (l) C) CH3OH (l) D) C2H6O2 (l)

C) CH3OH (l)

The complete photoelectron spectra of neutral atoms of two unknown elements, X and Y, are shown above. Which of the following can be inferred from the data? A) Element X has a greater electronegativity than element Y does. B) Element X has a greater ionization energy than element Y does. C) Element Y has a greater nuclear charge than element X does. D) The isotopes of element Y are approximately equal in abundance, but those of element X are not.

C) Element Y has a greater nuclear charge than element X does.

The elements I and Te have similar average atomic masses. A sample that was believed to be a mixture of I and Te was run through a mass spectrometer, resulting in the data above. All of the following statements are true. Which one would be the best basis for concluding that the sample was pure Te? A) Te forms ions with a −2 charge, whereas I forms ions with a −1 charge. B) Te is more abundant than I in the universe. C) I consists of only one naturally occurring isotope with 74 neutrons, whereas Te has more than one isotope. D) I has a higher first ionization energy than Te does.

C) I consists of only one naturally occurring isotope with 74 neutrons, whereas Te has more than one isotope.

The diagram above shows molecules of Br2 and I2 drawn to the same scale. Which of the following is the best explanation for the difference in the boiling points of liquid Br2 and I2, which are 59oC and 184oC, respectively? A) Solid iodine is a network covalent solid, whereas solid bromine is a molecular solid. B) The covalent bonds in I2 molecules are weaker than those in Br2 molecules. C) I2 molecules have electron clouds that are more polarizable than those of Br2 molecules, thus London dispersion forces are stronger in liquid I2. D) Bromine has a greater electronegativity than iodine, thus there are stronger dipole-dipole

C) I2 molecules have electron clouds that are more polarizable than those of Br2 molecules, thus London dispersion forces are stronger in liquid I2.

A compound contains 1.10 mol of K, 0.55 mol of Te, and 1.65 mol of O. What is the simplest formula of this compound? A) KTeO B) KTe2O C) K2TeO3 D) K2TeO6 E) K4TeO6

C) K2TeO3

The lattice energy of a salt is related to the energy required to separate the ions. For which of the following pairs of ions is the energy that is required to separate the ions largest? (Assume that the distance between the ions in each pair is equal to the sum of the ionic radii.) A) Na+(g) and Cl−(g) B) Cs+(g) and Br−(g) C) Mg2+(g) and O2−(g) D) Ca2+(g) and O2−(g)

C) Mg2+(g) and O2−(g)

On the basis of molecular structure and bond polarity, which of the following compounds is most likely to have the greatest solubility in water? A) CH4 B) CCl4 C) NH3 D) PH3

C) NH3

A compound contains 30. percent sulfur and 70. percent fluorine by mass. The empirical formula of the compound is A) SF B) SF2 C) SF4 D) SF6 E) S2F

C) SF4

Nonane and 2,3,4-trifluoropentane have almost identical molar masses, but nonane has a significantly higher boiling point. Which of the following statements best helps explain this observation? A) The C-F bond is easier to break than the C-H bond. B) The C-F bond is more polar than the C-H bond. C) The carbon chains are longer in nonane than they are in 2,3,4-trifluoropentane. D) The carbon chains are farther apart in a sample of nonane than they are in 2,3,4- trifluoropentane.

C) The carbon chains are longer in nonane than they are in 2,3,4-trifluoropentane

Based on the ionization energies of element X given in the table above, which of the following is most likely the empirical formula of an oxide of element X? A) XO2 B) X2O C) X2O3 D) X2O5

C) X2O3

The best explanation for the lower pressure in container 4 is that SO2 molecules A) have a larger average speed than the other three gases B) occupy a larger portion of the container volume than the other three gases C) have stronger intermolecular attractions than the other three gases D) contain π bonds, while the other gases contain only σ bonds

C) have stronger intermolecular attractions than the other three gases

The photoelectron spectra above show the energy required to remove a 1s electron from a nitrogen atom and from an oxygen atom. Which of the following statements best accounts for the peak in the upper spectrum being to the right of the peak in the lower spectrum? A) Nitrogen atoms have a half-filled p subshell. B) There are more electron-electron repulsions in oxygen atoms than in nitrogen atoms. C) Electrons in the p subshell of oxygen atoms provide more shielding than electrons in the p subshell of nitrogen atoms. D) Nitrogen atoms have a smaller nuclear charge than oxygen atoms.

D) Nitrogen atoms have a smaller nuclear charge than oxygen atoms.

A vessel contains Ar(g) at a high pressure. Which of the following statements best helps to explain why the measured pressure is significantly greater than the pressure calculated using the ideal gas law? A) The molar mass of Ar is relatively large. B) A significant number of Ar2 molecules form. C) The attractive forces among Ar atoms cause them to collide with the walls of the container with less force. D) The combined volume of the Ar atoms is too large to be negligible compared with the total volume of the container.

D) The combined volume of the Ar atoms is too large to be negligible compared with the total volume of the container.

In a paper chromatography experiment, a sample of a pigment is separated into two components, X and Y, as shown in the figure above. The surface of the paper is moderately polar. What can be concluded about X and Y based on the experimental results? A) X has a larger molar mass than Y does. B) Y has a larger molar mass than X does. C) X is more polar than Y. D) Y is more polar than X.

D) Y is more polar than X.

Three substances were studied in the laboratory, and the data in the table above were collected. Based on the data, which of the following shows the type of bonding in each substance?

D. Network Covalent, Metallic, Ionic

The elements in which of the following have most nearly the same atomic radius? A) Be, B, C, N B) Ne, Ar, Kr, Xe C) Mg, Ca, Sr, Ba D) C, P, Se, I E) Cr, Mn, Fe, Co

E) Cr, Mn, Fe, Co