ALL HW AND PROGRESS CHECKS

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 3d3 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. S206 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, H2O B. Ribose, C5H10O5 C. Fructose, C6H12O6, an isomer of glucose D. Sucrose, C12H22O11

A. Water, H2O

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

Cu(s) + 4 HNO3(aq) → Cu(NO3)2(aq) + 2 NO2(g) + 2 H2O(l) Each student in a class placed a 2.00 g sample of a mixture of Cu and Al in a beaker and placed the beaker in a fume hood. The students slowly poured 15.0 mL of 15.8 M HNO3(aq) into their beakers. The reaction between the copper in the mixture and the HNO3(aq) is represented by the equation above. The students observed that a brown gas was released from the beakers and that the solutions turned blue, indicating the formation of Cu2+(aq). The solutions were then diluted with distilled water to known volumes. The students determined that the reaction produced 0.010 mol of Cu(NO3)2 . Based on the measurement, what was the percent of Cu by mass in the original 2.00 g sample of the mixture? A. 16% B. 32% C. 64% D. 96%

B. 32%

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

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. Cr0 D. Cr2O E. Cr2O3

B. CrO2

M+ is an unknown metal cation with a +1 charge. A student dissolves the chloride of the unknown metal, MCl, in enough water to make 100.0 mL of solution. The student then mixes the solution with excess AgNO3 solution, causing AgCl to precipitate. The student collects the precipitate by filtration, dries it, and records the data shown below. (The molar mass of AgCl is 143 g/mol.) MASS OF UNKNOWN CHLORIDE, MCl 0.74g MASS OF FILTER PAPER 0.80g MASS OF FILTER PAPER PLUS AgCl PRECIPITATE 2.23g What is the identity of the metal chloride? A. NaCl B. KCl C. CuCl D. LiCl

B. KCl

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.

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-79 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.

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

When hafnium metal is heated in an atmosphere of chlorine gas, the product of the reaction is found to contain 62.2 percent Hf by mass and 37.4 percent Cl by mass. What is the empirical formula for this compound? A. HfCl B. HfCl2 C. HfCl3 D. HfCl4 E. Hf2Cl3

C. HfCl3

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 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

When a 3.22 g sample of an unknown hydrate of sodium sulfate, Na2SO4 ⋅ H2O(s), is heated, H2O (molar mass 18 g) is driven off. The mass of the anhydrous Na2SO4(s) (molar mass 142 g) that remains is 1.42 g. The value of x in the hydrate is A.0.013 B. 1.8 C. 6.0 D. 10 E. 20

D. 10

To gravimetrically analyze the silver content of a piece of jewelry made from an alloy of Ag and Cu, a student dissolves a small preweighed sample in HNO3(aq). Ag+(aq)and Cu2+(aq) ions form in the solution. Which of the following should be the next step in the analytical process? A. Centrifuging the solution to isolate the heavier ions B. Evaporating the solution to recover the dissolved nitrates C. Adding enough base solution to bring the pH up to 7.0 D. Adding a solution containing an anion that forms an insoluble salt with only one of the metal ions

D. Adding a solution containing an anion that forms an insoluble salt with only one of the metal ions

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(s). B. The sample contains NaCl(s) and NaI(s). C. The sample contains NaCl(s) and KCl(s). D. The sample contains NaCl(s) and LiCl(s).

D. The sample contains NaCl(s) and LiCl(s).

https://assets.learnosity.com/organisations/537/media.academicmerit.com/f6995c26e59d52ff88ac69872edc5c6f/original.png 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? A. X= Network Covalent Y= Ionic Z= Metallic B. X= Ionic Y= Molecular Z= Network Covalent C. X= Molecular Y= Network Covalent Z= Metallic D. X= Network Covalent Y= Metallic Z= Ionic

D. X= Network Covalent Y= Metallic Z= Ionic

Which of the following is the electron configuration of an excited atom that is likely to emit a quantum of energy? A. 1s2 2s2 2p6 3s2 3p1 B. 1s2 2s2 2p6 3s2 3p5 C. 1s2 2s2 2p6 3s2 D. 1s2 2s2 2p6 3s1 E. 1s2 2s2 2p6 3s1 3p1

E. 1s2 2s2 2p6 3s1 3p1

The percentage of silver in a solid sample is determined gravimetrically by converting the silver to Ag+(aq) and precipitating it as silver chloride. Failure to do which of the following could cause errors in the analysis? I. Account for the mass of the weighing paper when determining the mass of the sample II. Measure the temperature during the precipitation reaction III. Wash the precipitate IV. Heat the AgCl precipitate to constant mass A. I only B. I and II C. I and IV D. II and III E. I, III, and IV

E. I, III, and IV

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