ACS Gen Chem Practice Exam 77 Questions with Verified Answers
Which is the strongest oxidizing agent?
N a →← N a + + e - 2 . 7 1 V
Cd →←
... [Show More] Cd2+ + 2e- 0.40 V
H2 →← 2H+ +2e- 0.00V
Ag→← Ag++e- -0.80V
(A) Na+
(B)H2
(C) Cd0
(D)Ag+ - CORRECT ANSWER Ag+
All are examples of Lewis acid-base reactions except
Cu2+(aq) + 4NH3(aq) →← [Cu(NH3)4]2+(aq)
HCl(g) + NH3(g) → NH4Cl(s)
H+(aq) + OH-(aq) →← H2O(l)
2Na(s) + Cl2(g) → 2NaCl(s) - CORRECT ANSWER 2Na + Cl2 -> 2NaCl(s)
According to the Lewis definition, an acid is a species - CORRECT ANSWER accepting a pair of electrons
All are potential Lewis bases except
NH3
H2O
CH4
CN- - CORRECT ANSWER CH4
Which hydrated metal ion is most acidic under conditions of equal molar concentration in water? - CORRECT ANSWER Al3+
Which element in Group 5A forms the most basic oxide? - CORRECT ANSWER Bi
In what respect does an atom of magnesium differ from a magnesium ion (Mg^2+) - CORRECT ANSWER The ion has more stable electronic arrangement than the atom
A certain atom has the symbol 148/73Px. What does the symbol tell about an atom of the element? - CORRECT ANSWER It has 75 neutrons in the nucleus
The atomic mass of an element is 32.07 u and its atomic number is 16. The number of protons contained in the nucleus of an atom of this element is - CORRECT ANSWER 16
The atomic mass of an element is 32.07 u and its atomic number is 16. The element forms a simple ion. The ion will most likely have a charge of - CORRECT ANSWER 2-
Which atom contains 7 neutrons
A. n=1 n=2 n=3
M=24,z=12 2e 8e 2e
B. n=1 n=2 n=3
M=15 z=7 2e 5e
C. n=1 n=2 n=3
M=17, z=10 2e 8e
D. n=1 n=2 n=3
M=34, z=17 2e 8e 7e - CORRECT ANSWER C
In which pair of compounds should the first member be more covalent than the second member?
A TlCl, TlCl3
B SnI4,SnF4
C LiF, BF3
D SnF4, CF4 - CORRECT ANSWER SnI4, SnF4
Which is the most complete and best description of a covalent bond? - CORRECT ANSWER a system of nuclei where each atom donates one electron to the other atom, thus forming a bond
Which pair of elements is most likely to react to form a covalently bonded species?
A P and O
B Ca and O
C K and S
D Zn and C - CORRECT ANSWER P and O
Which chloride should exhibit the most covalent type of bond?
NaCl
KCl
CaCl2
BaCl2
BeCl2 - CORRECT ANSWER BeCl2
Which two elements are most likely to involve covalent bonding?
Q 0.9
R 1.0
T 2.8
X 3.0
Z 4.0 - CORRECT ANSWER T and X
Chromium metal can be plated from an acidic solution of CrO3.
How many grams of chromium will be plated by the passage of 19,300 C - CORRECT ANSWER 1.73g
What time is required to plate 2.08g of copper at a constant current flow of 1.26 A - CORRECT ANSWER 83.6
Nickel is a transition element and has a variable valence. Using a nickel salt, 2 F (faradays) plate out
39.2 g of nickel. What ions are in the solution of this salt? - CORRECT ANSWER Ni 3+
A given amount of electric charge deposits 2.159g of silver from AG^+ solution. What mass of copper Cu^2+ solution will be deposited by the same quantity of electric charge? - CORRECT ANSWER 0.635g
If each of these ions were reduced to metal with 1 C, which would yield the greatest mass? - CORRECT ANSWER Ag+
Which is a proper description of chemical equilibrium? - CORRECT ANSWER Reactant molecules are forming products as fast as product molecules are reacting to form reactants.
When equilibrium is reached in the reaction AE+CD -> CE +AD+x kJ in which all substances are in solution, - CORRECT ANSWER escape of some AD by volatilization will increase the concentration of CE.
Given the reaction 2X+Y -> 2Z Delta H =-335 kJ which combination of pressure and temperature gives the highest yield of Z at equilibrium? - CORRECT ANSWER 1000 atm and 100 °C
The reaction for the formation of ammonia by direct combination is
N2 + 3H2 -> 2NH3 Delta H=-92kJ
Which operation will increase the yield of ammonia in the equilibrium mixture? - CORRECT ANSWER doubling the concentration of hydrogen
Chemical equilibrium is the result of - CORRECT ANSWER Opposing reactions attaining equal speeds.
Complete and balance the equation for the equation for the combustion of ZnS in excess oxygen
?ZnS + ?O2 -> ?ZnO + ? - CORRECT ANSWER 2So2
Balance the equation for the reaction
? P + ? HNO3 + ? H2O -> ?H3PO4 + ?NO
The ratio of moles of oxidizing agent to moles of reducing agent in the balanced equation is - CORRECT ANSWER 2:5
Balance the equation for the reaction:
Cr2O3 + KOH + O2 -> K2CrO4 +H2O
What is the coefficient of KOH in the balanced equation is - CORRECT ANSWER 8
Why is the equation incorrect?
Mg3 + N2 -> Mg3N2 - CORRECT ANSWER Some of the subscripts are incorrectly used.
A lithium carbide reacts with water as follows
LixCy + H2O -> LiOH + C2H2 (unbalanced)
What is the simplest formula of the carbide? - CORRECT ANSWER LiC
In which gas are the forces between molecules strongest? - CORRECT ANSWER H2O
The density of a gas is 1.96 g*L^-1 at 1.00 atm and 0 C What is the density of this gas at 0.855 atm at 25.0 C - CORRECT ANSWER 1.54gL
A 1200 mL sample of helium is at a pressure of 350 mmHg and a temperature of 300K. What volume will this gas sample occupy if the pressure is increased to 700mmHg and the temperature is increased to 400K - CORRECT ANSWER 800mL
A sample of nitrogen at pressure P is contained in a sealed syringe with a movable piston. If the volume of the sample were doubled and the absolute temperature tripled, the new pressure of the gas would be - CORRECT ANSWER 1.5P
When equal volumes of 0.1 M solutions of HCl and NaOH are mixed, the total number of ions present will be approximately - CORRECT ANSWER half as great as before mixing
Oxygen and ozone have the formulas O2 and O3 respectively. They are - CORRECT ANSWER allotropes
Which instrument is directly used to determine the relative masses of atoms? - CORRECT ANSWER mass spectrograph
An enclosed mixture has a mass of 12.69723±0.00003 g, and after a chemical change occurs the
mixture has a mass of 12.69724±0.00003 g. These results show that - CORRECT ANSWER the mass of enclosed mixture remains constant within the experimental error of the measurement
The mechanism of electrical conduction in metals is thought to be - CORRECT ANSWER dependent on the movement of valence electrons
Which is not a characteristic of ionic substances? - CORRECT ANSWER Their reactions are generally extremely slow.
The addition of a catalyst in chemical reaction - CORRECT ANSWER provides an alternative path with a different activation energy
Which procedure will lower with activation energy for a particular reaction? - CORRECT ANSWER adding a catalyst
Which statement most accurately describes the behavior of a catalyst? - CORRECT ANSWER a catalyst reduces the activation energy for a reaction and increase the rate of a reaction
A catalyst will - CORRECT ANSWER Alter the pathway (mechanism) of a chemical reaction.
A student determines the mass of an object using a triple beam balance which is sensitive to 0.01 g. When the beam balances, the rider on one beam is in the notch marked 60 g, the rider on another beam in the notch marked 7 g, and the rider on the third beam, which is graduated by hundredths of a gram, is at zero. Considering significant figures, what mass should be recorded?A student determines the mass of an object using a triple beam balance which is sensitive to 0.01 g. When the beam balances, the rider on one beam is in the notch marked 60 g, the rider on another beam in the notch marked 7 g, and the rider on the third beam, which is graduated by hundredths of a gram, is at zero. Considering significant figures, what mass should be recorded? - CORRECT ANSWER 67.00 g
Which instrument is used to measure the gain or loss of heat? - CORRECT ANSWER calorimeter
What would be the most rapid method of preparing a saturated aqueous solution of KNO3 if the solubility is known? - CORRECT ANSWER add an excess over the calculated amount of solute to hot water and cool to 20C with stirring
Incandescent carbon particles cause a gas flame to be yellow. To obtain a hotter blue flame you should - CORRECT ANSWER open air holes
The electrical conductance of a solution of Ba(OH)2 slowly decreases upon the addition of H2SO4 to a minimum, and then slowly increases. The best experimental evidence for this is - CORRECT ANSWER An electric lamp placed in a circuit in series with the solution becomes dim as the H2SO4 is added and then becomes bright again.
Heating zinc sulfide in air causes the formation of - CORRECT ANSWER ZnO and SO2
Which group of ions can exist together in water solution in moderate concentration?
(A) Ba2+, NO3-, K+, CO32-
(B) Ba2+, Cl-, K+, SO42-
(C) K+, Cl-, Na+, NO3-
(D) Ag+, NO3-, K+, Cl-
(E) Na+, Pb2+, Cl-, NO3- - CORRECT ANSWER Ions are removed from the solution by the formation of water and insoluble BaSO4.
Which mixture will not yield hydrogen gas?
(A) sodium and water
(B) calcium and water
(C) zinc and hydrochloric acid
(D) zinc and concentrated nitric acid
(E) steam and red hot iron - CORRECT ANSWER K+, Cl-, Na+, NO3-
When sodium hydroxide solution is added to magnesium sulfate solution, a white precipitate of magnesium hydroxide is obtained. When sodium hydroxide solution is added to an "unknown" solution, a white precipitate is obtained. To conclude that the unknown solution contains magnesium ion, it must be assumed that - CORRECT ANSWER zinc and concentrated nitric acid
An sp hybridized central atom can be used to describe the bonding in - CORRECT ANSWER NaOH forms no white precipitate with any other ion except
Mg2
Which compound would be expected to have the largest dipole moment? - CORRECT ANSWER HCN
Which compound would be expected to have the largest dipole moment? - CORRECT ANSWER SO2 (bent)
Which is the largest bond angle? - CORRECT ANSWER angle F-Be-F in BeF2
Which molecule is polar? - CORRECT ANSWER H2S
Consider the reaction 2Fe3+(aq) + 2I-(aq) → 2Fe2+(aq) + I2(aq) Which statement is true for the reaction? - CORRECT ANSWER Fe 3+ is reduced
In the chemical reaction,
Zn(s) + CuSO4->ZnSO4+Cu
(A) metallic zinc is the reducing agent.
(B) metallic zinc in reduced.
(C) copper ion is oxidized.
(D) sulfate ion is the oxidizing agent. - CORRECT ANSWER metallic zinc is the reducing agent
In the chemical reaction, which substance behaves as the oxidizing agent?Pb + PbO2 + 2H2SO4 → 2PbSO4 + 2H2O - CORRECT ANSWER PbO2
In which group can each substance act as an oxidizing agent?
(A) Cl2, MnO2, Cu
(B)Cl2, MnO4-, Cu2+
(C)Cl-, MnO4-, Cu+
(D)Cl2, Mn, Cu2+ - CORRECT ANSWER Cl2, MnO4-, Cu2+
The molecule N2 is isoelectronic with
Formaldehyde, CH2O
Cyanide ion, CN-
Hydrogen, H2
Water, H2) - CORRECT ANSWER CN-
Which isoelectronic ion is the smallest in size?
Al^3+
Na^+
F^-
O^2- - CORRECT ANSWER Al3+
Which of these isoelectronic ions is the smallest?
Al^3+
Na^+
F^-
O^2-
Mg^2+ - CORRECT ANSWER Al3+
In which pair of particles is the first member larger than the second member?
(A) Li+ ; Be2+
(B) Li+ ; Li
(C) Li+ ; Na+
(D) Be ; Mg - CORRECT ANSWER Li+ ; Be2+
Which ion has the largest radius?
Cl-
F-
K+
Ca2+ - CORRECT ANSWER Cl-
The atomic molar mass of a hypothetical element X is 100 u. It is found that the 50.0 g of X combines with 32.0 g of oxygen. What is the simplest formula for the oxide of X?
(A) X2O
(B) XO2
(C) X2O3
(D) XO4 - CORRECT ANSWER XO4
An amino acid has a molar mass of 776.9 gmol^- and contains 65.34% iodine by mass. What is the number of iodine atoms per molecule of amino acid. - CORRECT ANSWER 4
A 6.80 g coin was dissolved in nitic acid and 6.21 g of AgCl was precipitated by the addition of excess sodium chloride.
Calculate the percentage of silver in the coin. - CORRECT ANSWER 75.3%
A 17.0 g sample of impure nickel metal reacts under standard conditions with 25.0L of CO to form 6.25L of Ni(CO)4 gas, what is the percentage of Ni in the metal sample? - CORRECT ANSWER 96.4%
Which molecule has the greatest bond energy?
(A) H—Br
(B) H—F
(C) H—At
(D) H—Cl
(E) H—I - CORRECT ANSWER H-F
For which process is the entropy change per mole the largest at constant temperature?
(A)H2O(l) → H2O(g)
(B)H2O(s) → H2O(g)
(C)H2O(s) → H2O(l)
(D)H2O(l) → H2O(s) - CORRECT ANSWER H2O(s) → H2O(g)
Under which conditions does nitrogen have the largest entropy per mole?
N2(s) at 50K and 1 atm
N2(l) at 70K and 1 atm
N2(g) at 80K and 1 atm
N2(g) at 80K and 0.5 atm - CORRECT ANSWER N2(g) at 80K and 0.5 atm
In which process is entropy decreased?
(A)dissolving sugar in water (B)expanding a gas
(C)evaporating a liquid
(D)freezing water - CORRECT ANSWER freezing water
Which reaction has the largest positive entropy change per mole of product formed?
(A) S(s) + 3F2(g) → SF6(g)
(B) SO2(g) + Na2O(s) → Na2SO3(s)
(C) Fe3+(aq) + SCN-(aq) → FeSCN2+(aq)
(D) H2O(l) → H2O(g) - CORRECT ANSWER H2O(l) → H2O(g) [Show Less]