General Chemistry ACS EXAM (2015 version) 60 Questions with Verified Answers
A 20.0 g sample of mercury(II) oxide (HgO, M = 216.6)
is heated strongly,
... [Show More] causing it to decompose to metallic Hg and O2 gas. What volume of O2 gas is produced
(measured at STP)?
(A) 1.03 L
(B) 2.07 L
(C) 4.14 L
(D) 14.0 L - CORRECT ANSWER A
When 30.0 mL of 0.10 M AgNO3 is added to 30.0 mL of
0.10 M NaCl, aqueous NaNO3 and solid AgCl are
formed. How much solid AgCl is produced?
(A) 0.0030 mol
(B) 0.0060 mol
(C) 0.030 mol
(D) 0.060 mol - CORRECT ANSWER A
How much Sr(OH)2 • 8 H2O (M = 265.76) is needed to
prepare 250.0 mL of solution in which [OH-] = 0.100 M?
(A) 3.32 g
(B) 6.64 g
(C) 9.97 g
(D) 13.3 g - CORRECT ANSWER A
A 10.00 g sample of a compound containing only carbon, hydrogen, and oxygen forms 23.98 g CO2 and 4.91 g H2O upon complete combustion. What is the empirical formula of the compound?
(A) C2HO
(B) C3H3O
(C) C6H3O2
(D) C6H6O - CORRECT ANSWER B
Which of the following is a nonelectrolyte in aqueous
solution?
(A) H2SO4
(B) NaC2H3O2
(C) K2CO3
(D) CH2O - CORRECT ANSWER D
An aqueous solution of potassium sulfate (K2SO4) has a freezing point of -2.24 ºC. What is its molality?
(Kf = 1.86 ºC•m-1)
(A) 0.401 m
(B) 0.602 m
(C) 1.20 m
(D) 4.17 m - CORRECT ANSWER A
Dissolution of which salt in water results in a decrease in the temperature of the solution?
A) KHSO4
(B) NaOH
(C) AlCl3
(D) NH4NO3 - CORRECT ANSWER D
What is observed when equal volumes of 0.1 M aqueous HCl and 0.01 M aqueous Na2SO3 are mixed?
(A) Colorless solution and a white precipitate
(B) Colored solution and a white precipitate
(C) Colorless solution and a colored precipitate
(D) Colorless solution, no precipitate, and gas
evolution - CORRECT ANSWER D
Which combination of dilute aqueous reagents will not
produce a precipitate?
(A) AgNO3 + HCl
(B) NaOH + HClO4
(C) BaBr2 + Na2SO4
(D) ZnI2 + KOH - CORRECT ANSWER B
A solution of a salt of which metal produces a bright red color in a flame test?
(A) Lithium
(B) Sodium
(C) Potassium
(D) Copper - CORRECT ANSWER A
Which cation forms a colorless aqueous solution?
(A) Co2+
(B) Ni2+
(C) Cu2+
(D) Zn2+ - CORRECT ANSWER D
Which 50-mL container would be most suitable for
measuring and dispensing 37 mL of an aqueous solution?
you need a picture for this. i just didnt want to take out this question bc i would probably the order of the answers up if i did lmfao - CORRECT ANSWER D (its a graduated cylinder)
A sample of O2 gas at a given temperature and pressure has a density of 1.30 g L-1. What is the density of gaseous propane (C3H8) under the same conditions?
(A) 1.30 g L-1
(B) 1.79 g L-1
(C) 1.96 g L-1
(D) 2.60 g L-1 - CORRECT ANSWER B
Which statements about the behavior of gaseous H2
molecules in a container at 1 atm and 298 K are correct?
I. All H2 molecules are moving at the same speed.
II. The H2 molecules are colliding more frequently with
the walls of the container than they would in the same
container at 398 K.
(A) I only
(B) II only
(C) Both I and II
(D) Neither I nor II - CORRECT ANSWER D
Which species has a normal boiling point closest to the
normal boiling point of argon, Ar?
(A) H2
(B) N2
(C) F2
(D) Cl2 - CORRECT ANSWER C
A sample of methanol, CH3OH, is introduced into an
evacuated chamber with a movable piston. The pressure is measured as a function of the volume of the container while the temperature is maintained at 50 ºC, and the graph below is obtained.
a graph is needed for this one so uhhhhhh. Thank u, next. - CORRECT ANSWER B
How many nearest neighbors does each silicon atom have in solid Si?
(A) 4
(B) 6
(C) 8
(D) 12 - CORRECT ANSWER A
Which sample contains the smallest number of atoms?
(A) 1.0 L of Ar at STP
(B) 1.0 L of H2 at STP
(C) 1.0 L of Ar at 25 ºC and 760 mm Hg
(D) 1.0 L of H2 at 0 ºC and 900 mm Hg - CORRECT ANSWER C
The standard enthalpy of formation, ∆Hºf, for HCOOH(l) is equal to the standard enthalpy change for which reaction?
(A) C(g) + 2 H(g) + 2 O(g) ---> HCOOH(l)
(B) C(s) + H2(g) + O2(g) ---> HCOOH(l)
(C) C(g) + H2(g) + O2(g) ---> HCOOH(l)
(D) CO2(g) + H2(g) ---> HCOOH(l) - CORRECT ANSWER B
40.0 mL of 0.200 M aqueous NaOH is added to 200.0
mL of 0.100 M aqueous NaHCO3 in a flask maintained at 25 ºC. Neglecting the effects of dilution, what is q for this reaction?
Solution ∆Hºf, kJ mol-1
OH-(aq) -230
HCO3-(aq) -692
CO3^2-(aq) -677
H2O(l) -286
(A) -41 J
(B) -74 J
(C) -330 J
(D) -820 J - CORRECT ANSWER C
In a well-insulated vessel, 50.0 g ice at 0.0 ºC is added to 350. g water at 32.0 ºC. What is the final temperature
when the mixture reaches equilibrium? (The heat of
fusion of ice is 334 J g-1.)
(A) 18.0 ºC
(B) 20.6 ºC
(C) 22.0 ºC
(D) 28.0 ºC - CORRECT ANSWER A
Which is the best explanation for the negative sign of ∆Sº in the following reaction?
CaSO4(s) ---> Ca2+(aq) + SO4^2-(aq)
∆Sº = -143 J mol-1 K^-1
(A) There are more ways of arranging the Ca2+ and SO4^2- ions in aqueous solution than in the crystal lattice.
(B) Solid CaSO4 is a network covalent solid, whereas it
separates into ions in aqueous solution.
(C) Aqueous Ca2+ and SO4^2- ions are tightly solvated,
decreasing the number of ways of arranging water
molecules when the solid dissolves.
(D) Calcium sulfate dissolves exothermically, leading to a net loss of entropy - CORRECT ANSWER C
The Ksp of Al(OH)3 is 2.0 x 10^-31 at 298 K. What is ∆Gº (at 298 K) for the precipitation of Al(OH)3 according to the equation below?
Al3+(aq) + 3 OH-(aq) ---> Al(OH)3(s)
(A) -175 kJ mol-1
(B) 14.7 kJ mol-1
(C) 70.6 kJ mol-1
(D) 175 kJ mol-1 - CORRECT ANSWER A
The bond dissociation enthalpies of the H-H bond and
the H-Cl bond are 435 kJ mol-1
and 431 kJ mol-1, respectively. The ∆Hºf of HCl(g) is -92 kJ mol-1. What is the bond dissociation enthalpy of the Cl-Cl bond?
(A) 88 kJ mol-1
(B) 96 kJ mol-1
(C) 188 kJ mol-1
(D) 243 kJ mol-1 - CORRECT ANSWER D
Which statement about chemical reaction mechanisms is correct?
(A) The overall rate law can be determined from any
step in the mechanism.
(B) The rate of a reaction is the rate of the fastest
elementary step of its mechanism.
(C) The chemical equation for the sum of all the
elementary steps is the chemical equation of the
overall reaction.
(D) Species that are produced and subsequently
consumed in the mechanism serve as catalysts for
the reaction. - CORRECT ANSWER C
At 280 ºC, nitrogen dioxide decomposes to nitric oxide
and oxygen:
2 NO2(g) ---> 2 NO(g) + O2(g)
In one experiment, the concentration of NO2 decreased from 0.0100 M to 0.0050 M over the course of 100. s. What was the average rate of disappearance of NO2(g)?
(A) 1.0 x 10^-2 M s-1
(B) 1.0 x 10^-4 M s-1
(C) 5.0 x 10^-5 M s-1
(D) 2.5 x 10^-5 M s-1 - CORRECT ANSWER C
What is the rate law for the following reaction?
A + 2 B C + D
There need to be a picture.....lmao...gtg. - CORRECT ANSWER C
What are the units of k if the rate law of a reaction is rate:
= k[X]0[Y]0?
(A) M s-1
(B) s-1
(C) M-1 s-1
(D) k is dimensionless - CORRECT ANSWER A
Hydrogen peroxide, H2O2(aq), decomposes into water
and oxygen. Adding a small amount of FeCl3(aq)
increases the rate of gas evolution in this reaction. What is the best description of the role of FeCl3?
(A) Transition state
(B) Reaction intermediate
(C) Heterogeneous catalyst
(D) Homogeneous catalyst - CORRECT ANSWER D
A substance decomposes in a first-order reaction with a rate constant of 6.70 x 10^-4 s-1. If the initial
concentration of the substance is 1.50 M, what is its
concentration after 500. s?
(A) 1.07 M
(B) 0.503 M
(C) 0.335 M
(D) 0.128 M - CORRECT ANSWER A
A 60.0 g sample of CaCO3 is heated to 950 K in a 1.00 L
evacuated container, where it reacts according to the
following equation:
CaCO3(s) <----> CaO(s) + CO2(g)
After equilibrium is attained, the pressure of CO2(g) is
30.0 mm Hg. When the experiment is repeated using
120.0 g CaCO3, what is the equilibrium pressure P?
(A) 15.0 mm Hg ≤ P < 30.0 mm Hg
(B) P = 30.0 mm Hg
(C) 30.0 mm Hg < P < 60.0 mm Hg
(D) P = 60.0 mm Hg - CORRECT ANSWER B
Nitrous acid, HNO2, has Ka = 4.5 10-4. What is the best description of the species present in a 0.1 M solution of nitrous acid?
(A) HNO2(aq) is the predominant species; much smaller amounts of H+(aq) and NO2-(aq) exist.
(B) H+(aq) and NO2-(aq) are the predominant species;
much smaller amounts of HNO2(aq) exist.
(C) Only H+(aq) and NO2-(aq) are present in measurable
amounts.
(D) HNO2(aq), H+(aq), and NO2-(aq) are all present in
comparable amounts - CORRECT ANSWER A
Silver sulfate, Ag2SO4 (M = 311.87), has Ksp = 6.0 10-5.
What mass of Ag2SO4 will dissolve per liter of water?
(A) 0.019 g
(B) 1.7 g
(C) 2.4 g
(D) 7.7 g - CORRECT ANSWER D
IBr(g) is in equilibrium with I2(g) and Br2(g) at 150 ºC:
2 IBr(g) I2(g) + Br2(g) K = 8.50 x 10^-3.
Initially, a closed vessel at 150 ºC has a partial pressure
of IBr of 0.350 atm and partial pressures of I2 and Br2
each of 0.750 atm. What is the partial pressure of IBr
once the system reaches equilibrium?
(A) 1.01 atm
(B) 1.09 atm
(C) 1.56 atm
(D) 1.82 atm - CORRECT ANSWER C
20 mL of an approximately 10% aqueous solution of
ethylamine, CH3CH2NH2, is titrated with 0.3000 M
aqueous HCl. Which indicator would be most suitable
for this titration? The pKa of CH3CH2NH3 + is 10.75.
(A) Thymol blue, color change from pH = 1.2 to 2.8
(B) Bromocresol green, color change from pH = 4.0 to
5.6
(C) Phenolphthalein, color change from pH = 8.0 to 10.0
(D) Alizarin yellow R, color change from pH = 10.0 to
12.0 - CORRECT ANSWER B
The tetramminecopper(II) ion, Cu(NH3)4
2+, has a formation constant Kf = 1.1 1013. What is the minimum concentration of free ammonia in solution required to ensure that at least 99.9% of the dissolved copper(II) ion is found in the form of its ammonia complex?
(A) 9 x 10^-14 M
(B) 9 x 10^-11 M
(C) 8 x 10^-4 M
(D) 3 x 10^-3 M - CORRECT ANSWER D
When the equation
ClO2(aq) + OH-(aq) ---> ClO2-(aq) + ClO3-(aq) + H2O(l) is balanced, what is the ratio of the coefficient of ClO2 to that of ClO3- ?
(A) 1 : 1
(B) 2 : 1
(C) 3 : 1
(D) 3 : 2 - CORRECT ANSWER B
When an aqueous solution of KI is electrolyzed, what
forms at the anode?
(A) O2
(B) I2
(C) K
(D) H2O - CORRECT ANSWER B
A current of 0.15 A is passed through an aqueous solution of K2PtCl4. How long will it take to deposit 1.00 g Pt(s) (M = 195.1)?
(A) 1600 s
(B) 3300 s
(C) 6600 s
(D) 13000 s - CORRECT ANSWER C
In the galvanic cell
Al(s) ǀ Al3+(aq, 1 M) ǀǀ Cu2+(aq, 1 M) ǀ Cu(s)
which of the following changes will increase the cell
potential?
I. Dilution of the Al3+ solution to 0.001 M
II. Dilution of the Cu2+ solution to 0.001 M
III. Increasing the surface area of the Al(s) electrode
(A) I only
(B) II only
(C) III only
(D) I and III only - CORRECT ANSWER A
What is the equilibrium constant for the following
reaction at 25 °C?
2 Ag+(aq) + Cu(s) → Cu2+(aq) + 2 Ag(s)
Half-Reaction Eº, V
Ag+(aq) + e- ---> Ag(s) +0.80
Cu2+(aq) + 2e- ---> Cu(s) +0.34
A) 6.0 x 10^7
(B) 3.6 x 10^15
(C) 3.6 x 10^38
(D) 4.2 x 10^4 - CORRECT ANSWER B
In the galvanic cell
Sn(s) | Sn2+(aq) || Cu2+(aq) | Cu(s)
the standard potential is 0.48 V. Starting with standard
concentrations, what are the concentrations of Sn2+ and Cu2+ when the cell has discharged to a potential of 0.45 V?
(A) [Sn2+ ] = 0.47 M, [Cu2+] = 1.53 M
(B) [Sn2+ ] = [Cu2+] = 1.00 M
(C) [Sn2+ ] = 1.53 M, [Cu2+] = 0.47 M
(D) [Sn2+ ] = 1.82 M, [Cu2+] = 0.18 M - CORRECT ANSWER D
Which of the following statements is best supported by
the data from Rutherford's experiment of scattering alpha particles with a thin metal foil?
(A) The mass and positive charge of an atom are
concentrated in its center.
(B) Electrons in atoms occupy only certain specific
energy levels.
(C) Moving particles can also be described as waves.
(D) Atoms of a given element do not all have identical
masses - CORRECT ANSWER A
What is the formula of the most stable oxide of francium?
(A) Fr2O
(B) FrO
(C) Fr2O3
(D) FrO - CORRECT ANSWER A
As atomic number increases from 11 to 15, the atomic
radii of the elements
(A) increase
(B) decrease
(C) increase, then decrease
(D) decrease, then increase - CORRECT ANSWER B
Nitrogen has a greater first ionization energy than
oxygen. What is the best explanation for this
observation?
(A) Nitrogen is more electronegative than oxygen.
(B) A nitrogen atom is smaller than an oxygen atom.
(C) The electron ionized from nitrogen experiences
less electron-electron repulsion than the electron
ionized from oxygen.
(D) The electron ionized from nitrogen is a 2s electron,
while the electron ionized from oxygen is a 2p
electron. - CORRECT ANSWER C
Which set of quantum numbers n, l, ml, ms is invalid?
(A) 1, 1, 0, -½
(B) 2, 0, 0, +½
(C) 3, 1, 0, +½
(D) 4, 3, 2, -½ - CORRECT ANSWER A
What is the product of alpha emission from the isotope
uranium-238?
(A) 232^Th
(B) 234^Th
(C) 237^Np
(D) 231^Pa - CORRECT ANSWER B
Which molecule is nonpolar, yet contains polar covalent bonds?
(A) CO2
(B) HCN
(C) NH3
(D) P4 - CORRECT ANSWER A
The nitrite ion, NO2-, can be represented as a resonance hybrid of two significant Lewis structures. Which statements about this are correct?
I. The two resonance structures contribute equally to the structure.
II. The formal charge of nitrogen is zero in both
resonance structures.
(A) I only
(B) II only
(C) Both I and II
(D) Neither I nor II - CORRECT ANSWER C
Which is not a stable molecule?
(A) NF3
(B) NF5
(C) PF3
(D) PF5 - CORRECT ANSWER B
What is the molecular geometry of IF3?
(A) Trigonal planar
(B) Trigonal pyramidal
(C) T-shaped
(D) Tetrahedral - CORRECT ANSWER C
N2 is a stable molecule and the N4 molecule is unknown. P4 is much more stable than molecular P2. Which is the best explanation for this difference?
(A) N2 has valence electrons only in bonding and
nonbonding orbitals, while P2 has some valence
electrons in antibonding orbitals.
(B) The greater electronegativity of N compared to P
stabilizes compounds with lower molar masses.
(C) The greater size of P compared to N results in
decreased overlap in pi bonds.
(D) The preference of P to adopt smaller bond angles
than N favors formation of tetrahedral P4 molecules. - CORRECT ANSWER C
Which contains sp3- hybridized carbon atoms?
(A) Benzene, C6H6
(B) Ethane, C2H6
(C) Ethene, C2H4
(D) Ethyne, C2H2 - CORRECT ANSWER B
How many sigma bonds are in 2-butyne
(CH3C (triple bond)CCH3)?
(A) 3
(B) 6
(C) 9
(D) 11 - CORRECT ANSWER C
Which alcohol will undergo acid-catalyzed dehydration
under the mildest conditions?
(A) CH3CH2CH2CH2OH
(B) CH3CH2CH(OH)CH3
(C) (CH3)2CHCH2OH
(D) (CH3)3COH - CORRECT ANSWER D
A 1.0 M aqueous solution of which compound has the
lowest pH?
(A) CH3CH2OH
(B) CH3COOH
(C) CH3CHO
(D) Cl3CCHO - CORRECT ANSWER B
A six-carbon organic compound containing oxygen is
suspected of being either a secondary alcohol or a ketone. Which chemical or physical test would best distinguish between these two possibilities?
(A) Water solubility
(B) Melting point
(C) Treatment with sodium bicarbonate
(D) Treatment with acidic dichromate - CORRECT ANSWER D
Which two bases are found as a hydrogen-bonded base pair in DNA?
(A) A and T
(B) C and T
(C) C and U
(D) G and U - CORRECT ANSWER A
What is the nature of the peptide bonds in a protein?
(A) Hydrogen bonds
(B) Amide bonds
(C) Disulfide bonds
(D) Ionic bonds - CORRECT ANSWER B [Show Less]