AP Chem Quiz 1.1

A solution is prepared by adding 16 g of CH3OH (molar mass 32 g) to 90. g of H2O (molar mass 18 g). The mole fraction of CH3OH in this solution is closest to which of the following? A. 0.1 B. 0.2 C. 0.3 D. 0.4 E. 0.6

A. 0.1

How many carbon atoms are contained in 2.8 g of C2H4 ? A. 1.2 x 10^23 B. 3.0 x 10^23 C. 6.0 x 10^23 D. 1.2 x 10^24 E. 6.0 x 10^24

A. 1.2 x 10^23

Which of the following represents the ground state electron configuration for the Mn3+ ion? (Atomic number Mn = 25) A. 1s2 2s2 2p6 3s2 3p6 3d4 B. 1s2 2s2 2p6 3s2 3p6 3d5 4s2 C. 1s2 2s2 2p6 3s2 3p6 3d2 4s2 D. 1s2 2s2 2p6 3s2 3p6 3d8 4s2 E. 1s2 2s2 2p6 3s2 3p6 3d8 4s1

A. 1s2 2s2 2p6 3s2 3p6 3d4

Consider atoms of the following elements. Assume that the atoms are in the ground state. The atom that contains exactly two unpaired electrons A. S B. Ca C. Ga D. Sb E. Br

A. S

If a pure sample of an oxide of sulfur contains 40. percent sulfur and 60. percent oxygen by mass, then the empirical formula of the oxide is A. SO3 B. SO4 C. S2O6 D. S2O8

A. SO3

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, H20 B. Ribose, C5H10O5 C. Fructose, C6H12O6 D. Sucrose, C12H22O11

A. Water, H20

A student has samples of two pure compounds, XClO3 and ZClO3, which contain unknown alkali metals X and Z. The student measures the mass of each sample and then strongly heats the samples to drive off all the oxygen, leaving solid residues of XCl and ZCl. The student measures the mass of the solid residue from each sample. Which of the following questions can be answered from the results of the experiment? A. Which has the greater molar mass, X or Z? B. Which has the higher boiling point, X or Z? C. Which has the higher melting point, XCl or ZCl? D. Which has the greater density, XCl or ZCl?

A. Which has the greater molar mass, X or Z?

A student has two samples of NaCl, each one from a different source. Assume that the only potential contaminant in each sample is KCl. The student runs an experiment to determine the percent by mass of chlorine in each sample. From the results of this experiment alone, which of the following questions is most likely to be answered? A. Which sample has the higher purity? B. Which sample has the higher density? C. What is the source of the contaminants present in each of the samples? D. Which sample came from a salt mine, and which sample came from the ocean?

A. Which sample has the higher purity?

The mass spectrum of the element Sb is most likely represented by which of the following? A. 122 Atomic Mass B. 121 and 123 Atomic Mass C. 120, 123 and 124 Atomic Mass D. 120,121 and 124 Atomic Mass

B. 121 and 123 Atomic Mass

Of the following electron configurations of neutral atoms, which represents an atom in an excited state? A. 1s2 2s2 2p5 B. 1s2 2s2 2p5 3s2 C. 1s2 2s2 2p6 3s1 D. 1s2 2s2 2p6 3s2 3p2 E. 1s2 2s2 2p6 3s2 3p5

B. 1s2 2s2 2p5 3s2

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

B. C2H6O

A sample of a compound that contains only the elements C, H, and N is completely burned in O2 to produce 44.0 g of CO2, 45.0 g of H2O, and some NO2 . A possible empirical formula of the compound is A. CH2N B. CH5N C. C2H5N D. C3H3N2

B. CH5N

In which of the following compounds is the mass ratio of chromium to oxygen closest to 1.62 to 1.00? A. CrO3 B. CrO2 C. CrO D. Cr2O E. Cr2O3

B. CrO2

The mass spectrum of a sample of a pure element is shown above. Based on the data, the peak at 26amu represents an isotope of which of the following elements? A. Al with 13 neutrons B. Mg with 14 neutrons C. Fe with 26 neutrons D. Ti with 26 neutrons

B. Mg with 14 neutrons

Which of the following elements has the mass spectrum represented above? A. Nb B. Mo C. U D. Cf

B. Mo

Which of the following shows the correct number of protons, neutrons, and electrons in a neutral cesium-134 atom? A. P= 55 N= 55 E= 55 B. P= 55 N= 79 E= 55 C. P= 55 N= 55 E= 79 D. P= 79 N= 55 E= 79 E. P= 134 N= 55 E= 134

B. P= 55 N= 79 E= 55

After completing an experiment to determine gravimetrically the percentage of water in a hydrate, a student reported a value of 38 percent. The correct value for the percentage of water in the hydrate is 51 percent. Which of the following is the most likely explanation for this difference? A. Strong initial heating caused some of the hydrate sample to spatter out of the crucible B. The dehydrated sample absorbed moisture after heating C. The amount of the hydrate sample used was too small D. The crucible was not heated to constant mass before use E. Excess heating caused the dehydrated sample to decompose

B. The dehydrated sample absorbed moisture after heating

A student is given two 10g samples, each a mixture of only NaCl(s) and KCl(s) but in different proportions. Which of the following pieces of information could be used to determine which mixture has the higher proportion of KCl(s) ? A. The volume of each mixture B. The mass of Cl in each mixture C. The number of isotopes of Na and K D. The reaction of each mixture with water

B. The mass of Cl in each mixture

Two different ionic compounds each contain only copper and chlorine. Both compounds are powders, one white and one brown. An elemental analysis is performed on each powder. Which of the following questions about the compounds is most likely to be answered by the results of the analysis? A. What is the density of each pure compound? B. What is the formula unit of each compound? C. What is the chemical reactivity of each compound? D. Which of the two compounds is more soluble in water?

B. What is the formula unit of each compound?

The mass spectrum of an average sample of a pure element is shown in the figure above. Which of the following is the identity of the element? A. Y B. Zr C. Nb D. Th

B. Zr

Which of the following numerical expressions gives the number of particles in 2.0g of Ne? A. 6.0x10^23 particles/2.0g B. 6.0x10^23 particles/20.18g C. 2.0g/20.18g (6.0x10^23 particles) D. 20.18x10^23 particles/2.0g(6.0x10^23 particles)

C. 2.0g/20.18g (6.0x10^23 particles)

A sample of carbonate rock is a mixture of CaCO3 and MgCO3. The rock is analyzed in a laboratory, and the results are recorded in the table above. Which columns in the table provide all the information necessary to determine the mole ratio of Ca to Mg in the rock? A. 1,2,5 B. 2,5,6 C. 3,4,6,7 D. 2,3,4,5

C. 3,4,6,7

In 1.00 mol of potassium zirconium sulfate trihydrate, K4Zr(SO4)4 • 3 H2O, there are A. 3 x 6.02 x 10^23 hydrogen atoms B. 6.02 x 10^23 hydrogen atoms C. 4 x 6.02 x 10^23 hydrogen atoms D. 4 moles of oxygen atoms E. 4 moles of zirconium atoms

C. 4 x 6.02 x 10^23 hydrogen atoms

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

Consider atoms of the following elements. Assume that the atoms are in the ground state. The atom that contains only one electron in the highest occupied energy sublevel A. S B. Ca C. Ga D. Sb E. Br

C. Ga

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

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

A student obtains a sample of a pure solid compound. In addition to Avogadro's number, which of the following must the student know in order to determine how many molecules are in the sample? A. Mass of the sample, volume of the sample B. Mass of the sample, density of the sample C. Molar mass of the compound, mass of the sample D. Molar mass of the compound, density of the sample

C. Molar mass of the compound, mass of the sample

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

What number of moles of O2 is needed to produce 14.2 grams of P4O10 from P? (Molecular weight P4O10 = 284) A. 0.0500 mole B. 0.0625 mole C. 0.125 mole D. 0.250 mole E. 0.500 mole

D. 0.250 mole

A solution of methanol, CH3OH, in water is prepared by mixing together 128 g of methanol and 108 g of water. The mole fraction of methanol in the solution is closest to A. 0.80 B. 0.60 C. 0.50 D. 0.40 E. 0.20

D. 0.40

A sample of CaCO3 (molar mass 100. g) was reported as being 30. percent Ca. Assuming no calcium was present in any impurities, the percent of CaCO3 in the sample is A. 30% B. 40% C. 70% D. 75% E. 100%

D. 75%

A student has a 1g sample of each of the following compounds: NaCl, KBr, and KCl. Which of the following lists the samples in order of increasing number of moles in the sample? A. NaCl<KCl<KBr B. NaCl<KBr<KCl C. KCl<NaCl<KBr D. KBr<KCl<NaCl

D. KBr<KCl<NaCl

The mass spectrum of element X is presented in the diagram above. Based on the spectrum, which of the following can be concluded about element X? A. X is a transition metal, and each peak represents an oxidation state of the metal B. X contains five electron sub levels C. The atomic mass of X is 90 D. The atomic mass of X is between 90 and 92

D. The atomic mass of X is between 90 and 92

A 5.0g sample of MgCl2 may contain measurable amounts of other compounds as impurities. Which of the following quantities is (are) needed to determine that the sample is pure MgCl2 ? A. The color and density of the sample B. The mass of Mg in the sample only C. The number of moles of Cl in the sample only D. The mass of Mg and the mass of Cl in the sample

D. The mass of Mg and the mass of Cl in the sample

A sample of a solid labeled as NaCl may be impure. A student analyzes the sample and determines that it contains 75 percent chlorine by mass. Pure NaCl(s) contains 61 percent chlorine by mass. Which of the following statements is consistent with the data? A. The sample contains only NaCl B. The sample contains NaCl and NaI C. The sample contains NaCl and KCl D. The sample contains NaCl and LiCl

D. The sample contains NaCl and LiCl

A sample of a compound contains 3.21 g of sulfur and 11.4 g of fluorine. Which of the following represents the empirical formula of the compound? A. SF2 B. SF3 C. SF4 D. SF5 E. SF6

E. SF6