1091 1st Midterm Exam _11/04/20_(A)
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
1) Calculate the percentage by mass of lead in Pb(NO3)2.
A) 44.5 B) 71.2 C) 62.6 D) 38.6 E) 65.3
Answer: C
2) Lithium and nitrogen react in a combination reaction to produce lithium nitride:
6Li (s) + N2 (g) → 2Li3N (s)
In a particular experiment, 2.50-g samples of each reagent are reacted. The theoretical yield of lithium nitride is ________ g.
A) 2.09 B) 2.51 C) 6.2 D) 12.5 E) 4.18
Answer: E
3) When the following equation is balanced, the coefficient of sulfur dioxide is ________.
PbS (s) + O2 (g) → PbO (s) + SO2 (g)
A) 2 B) 1 C) 5 D) 4 E) 3
Answer: A
4) What is the maximum amount in grams of SO3 that can be produced by the reaction of 1.0 g of S with 1.0 g of O2 via the equation below?
S (s) + O2(g) → SO3 (g) (not balanced)
A) 1.7 B) 2.5 C) 3.8 D) 0.27 E) 2.0
Answer: A
5) Combustion of a 1.031-g sample of a compound containing only carbon, hydrogen, and oxygen produced 2.265 g of CO2 and 1.236 g of H2O. What is the empirical formula of the compound?
A) C3H9O3 B) C3H5O C) C6H16O2 D) C3H6O3 E) C3H8O
Answer: E
6) There are ________ sulfur atoms in 25 molecules of C4H4S2.
A) 6.02 × 1023 B) 1.5 × 1025 C) 3.0 × 1025 D) 4.8 × 1025 E) 50 Answer: E
7) How many carbon atoms are there in 52.06 g of carbon dioxide?
A) 5.206 × 1024 B) 7.122 × 1023 C) 1.424 × 1024 D) 3.134 × 1025 E) 8.648 × 10-23 Answer: B
8) What is the empirical formula of a compound that contains 49.4% K, 20.3% S, and 30.3% O by mass?
A) KSO4 B) KSO2 C) K2SO3 D) K2SO4 E) KSO3
Answer: C
9) One mole of ________ contains the smallest number of atoms.
A) Na3PO4 B) Al2(SO4)3 C) S8 D) C10H8 E) NaCl
Answer: E
10) An element cannot ________.
A) be part of a heterogeneous mixture
B) interact with other elements to form compounds C) be separated into other substances by chemical means D) be part of a homogeneous mixture
E) be a pure substance Answer: C
11) A 4.369 g sample of metal is placed in a flask. Water is added to the flask and the total volume in the flask is read to be 126.4 ml. The mass of the water, flask, and metal is 268.5 g. If the mass of the flask is 139.3 g and the density of water is 1.000 g/mL, the density of the solid is ________ g/cm3.
A) 2.78 B) 0.641 C) 3.21 D) 1.56 E) 0.366
Answer: A
12) The quantity 1.0 mg/cm2 is the same as 1.0 × ________ kg/m2.
A) 10-4 B) 10-6 C) 104 D) 102 E) 10-2
Answer: E
13) The number 1.00430 has ________ significant figures.
A) 4 B) 2 C) 6 D) 3 E) 5
Answer: C
14) Convert -41.0°F to degrees Celsius.
A) -40.6°C B) -73.0°C C) -117°C D) -9.0°C E) -57.6°C
Answer: A
15) Which of the following is a physical property?
A) the density of lead
B) platinum metal does not react with hydrochloric acid C) ozone reacts with silver to give silver oxide
D) sulfur burns in oxygen to form sulfur trioxide Answer: A
16) The correct result (indicating the proper number of significant figures) of the following calculation of the molecular mass for H2SO4 is ________.
4 × 15.9994 + 32.066 + 2 × 1.0079
17) Which one of the following is often easily separated into its components by simple techniques such as filtering or decanting?
A) compounds
B) homogeneous mixture C) heterogeneous mixture D) elements
E) solutions Answer: C
18) Different isotopes of a particular element contain different numbers of ________.
A) protons B) neutrons
C) protons, neutrons, and electrons D) protons and neutrons
E) None of the above is correct.
Answer: B
19) Which species is an isotope of 39Cl?
A) 39Ar B) 40Ar+ C) 36Cl- D) 34S2- E) 80Br
Answer: C
20) Which isotope has 36 electrons in an atom?
A) 7834Se B) 3680Hg C) 8035Br D) 3417Cl E) 8036Kr
Answer: E
21) The correct formula for molybdenum (IV) hypochlorite is ________.
A) Mo(ClO3)4 B) Mo(ClO4)4 C) Mo(ClO2)4 D) Mo(ClO)4 E) MoCl4
Answer: D
22) The charge on the silver ion in the salt AgCl is ________.
A) +3 B) +2 C) +1 D) +5 E) +4
Answer: C
23) Which atom has the smallest number of neutrons?
A) oxygen-16 B) carbon-14 C) neon-20 D) nitrogen-14 E) fluorine-19
Answer: D
24) ________ typically form ions with a 2+ charge.
A) Alkaline earth metals B) Chalcogens
C) Halogens
D) Transition metals E) Alkali metals Answer: A
25) The empirical formula of a compound with molecules containing 12 carbon atoms, 14 hydrogen atoms, and 6 oxygen atoms is ________.
A) C6H7O3 B) C2H4O C) CHO D) C12H14O6 E) CH2O
Answer: A
26) The average atomic weight of copper, which has two naturally occurring isotopes, is 63.5. One of the isotopes has an atomic weight of 62.9 amu and constitutes 69.1% of the copper isotopes. The other isotope has an abundance of 30.9%. The atomic weight (amu) of the second isotope is ________ amu.
A) 64.8 B) 28.1 C) 63.8 D) 63.2 E) 64.1
Answer: A
27) The correct name for N2O5 is ________.
A) nitrogen oxide B) nitrogen pentoxide C) nitrous oxide D) nitric oxide
E) dinitrogen pentoxide Answer: E
28) The ions Ca2+ and PO43- form a salt with the formula ________.
A) Ca3(PO4)2 B) CaPO4 C) Ca2(PO4)3 D) Ca2PO4 E) Ca(PO4)2
Answer: A
29) What is the molarity of a NaOH solution if 15.5 mL of a 0.220 M H2SO4 solution is required to neutralize a 25.0-mL sample of the NaOH solution?
A) 0.355 B) 0.136 C) 0.273 D) 42.6 E) 0.710
Answer: C
30) What is the concentration (M) of CH3OH in a solution prepared by dissolving 34.4 g of CH3OH in sufficient water to give exactly 230 mL of solution?
A) 11.9 B) 1.59 C) 4.67 D) 0.00159 E) 5.31
Answer: C
31) What mass (g) of barium iodide is contained in 188 mL of a barium iodide solution that has an iodide ion concentration of 0.532 M?
A) 39,100 B) 39.1 C) 276 D) 19.6 E) 19,600
Answer: D
32) Calculate the concentration (M) of sodium ions in a solution made by diluting 50.0 mL of a 0.874 M solution of sodium sulfide to a total volume of 250.0 mL.
A) 0.350 B) 4.37 C) 0.525 D) 0.175 E) 0.874
Answer: A
33) In which species does nitrogen have the highest oxidation number?
A) NO2- B) NH3 C) N2 D) NaNO3 E) HNO2
34) When aqueous solutions of Pb(NO3)2 and NaCl are mixed, PbCl2 precipitates. The balanced net ionic equation is ________.
A) Pb2+ (aq) + 2NO3- (aq) → Pb(NO3)2 (s) B) Pb2+ (aq) + 2Cl- (aq) → PbCl2 (s)
C) Pb2+ (aq) + 2NO3- (aq) → Pb(NO3)2 (aq)
D) Pb(NO3)2 (aq) + 2NaCl (aq) → PbCl2 (aq) + 2NaNO3 (s) E) Pb(NO3)2 (aq) + 2NaCl (aq) → PbCl2 (s) + 2NaNO3 (aq) Answer: B
35) Which one of the following is a diprotic acid?
A) phosphoric acid B) sulfuric acid C) hydrofluoric acid D) nitric acid
E) chloric acid Answer: B
36) Which one of the following compounds is insoluble in water?
A) Na2CO3 B) ZnS C) AgNO3 D) K2SO4 E) Fe(NO3)3
Answer: B
37) Which combination will produce a precipitate?
A) NaOH (aq) and Sr(NO3)2 (aq) B) Pb(NO3)2 (aq) and HCl (aq) C) Cu(NO3)2 (aq) and KC2H3O2 (aq) D) AgC2H3O2 (aq) and HC2H3O2 (aq)
E) KOH (aq) and HNO3 (aq) Answer: B
38) Which of the following is an oxidation-reduction reaction?
A) Ba(C2H3O2)2 (aq) + Na2SO4 (aq) → BaSO4 (s) + 2NaC2H3O2(aq) B) AgNO3 (aq) + HCl (aq) → AgCl (s) + HNO3 (aq)
C) Cu (s) + 2AgNO3 (aq) → 2Ag (s) + Cu(NO3)2 (aq) D) HCl (aq) + NaOH (aq) → H2O (l) + NaCl (aq)
E) H2CO3 (aq) + Ca(NO3)2 (aq) → 2HNO3 (aq) + CaCO3 (s) Answer: C
39) The point in a titration at which the indicator changes is called the ________.
A) indicator point B) end point C) volumetric point D) setpoint
E) standard point Answer: B
40) How many moles of Na+ are present in 343 mL of a 1.27 M solution of Na2SO4?
A) 0.436 B) 3.70 C) 1.31 D) 0.871 E) 11.1
Answer: D
