Chem Aug 2010 Regents
(182).webp "Chem Aug 2010 Regents - Quiz")
Multiple choice + explanations.
- 1.
What is the total number of valence electrons in a calcium atom in the ground state?
- A.
8
- B.
2
- C.
18
- D.
20
Correct Answer
B. 2Explanation
the last number of the configuration is the valence electronsRate this question:
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- 2.
Which subatomic particles are located in the nucleus of an He-4 atom?
- A.
Electrons and neutrons
- B.
Electrons and protons
- C.
Neutrons and protons
- D.
Neutrons, protons, and electrons
Correct Answer
C. Neutrons and protonsExplanation
electrons are in orbitals around the nucleus.Rate this question:
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- 3.
In the late 1800s, experiments using cathode ray tubes led to the discovery of the
- A.
Electrons
- B.
Neutrons
- C.
Protons
- D.
Positrons
Correct Answer
A. ElectronsExplanation
Using the cathode ray tube enabled the scientists to discover that negatively charged particles exist outside the nucleus.Rate this question:
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- 4.
The atomic mass of titanium is 47.88 atomic mass units. This atomic mass represents the
- A.
Total mass of all the protons and neutrons in an atom of Ti
- B.
Total mass of all the protons, neutrons, and electrons in an atom of Ti
- C.
Weighted average mass of the most abundant isotope of Ti
- D.
Weighted average mass of all the naturally occurring isotopes of Ti
Correct Answer
D. Weighted average mass of all the naturally occurring isotopes of TiExplanation
atomic mass equals the weighted average of the naturally occurring isotopes.Rate this question:
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- 5.
An atom of which element has the largest atomic radius?
- A.
Fe
- B.
Mg
- C.
Si
- D.
Zn
Correct Answer
B. MgExplanation
This one's a bit tricky...magnesium has fewer orbitals, but it also has only two valence electrons, which makes it the largest.
WHEN IN DOUBT, CHECK OUT TABLE S!!!Rate this question:
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- 6.
Which element requires the least amount of energy to remove the most loosely held electron from a gaseous atom in the ground state?
- A.
Bromine
- B.
Calcium
- C.
Sodium
- D.
Silver
Correct Answer
C. SodiumExplanation
sodium only has one valence electron, which is NOT held very strongly.
WHEN IN DOUBT, CONSULT TABLE S.Rate this question:
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- 7.
A balanced equation representing a chemical reaction can be written using
- A.
Chemical formulas and mass numbers
- B.
Chemical formulas and coefficients
- C.
First ionization energies and mass numbers
- D.
First ionization energies and coefficients
Correct Answer
B. Chemical formulas and coefficientsExplanation
Chemical formulas are the atomic symbols and the coefficients are the numbers in front of the symbols.Rate this question:
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- 8.
Every water molecule has two hydrogen atoms bonded to one oxygen atom. This fact supports the concept that elements in a compound are
- A.
Chemically combined in a fixed proportion
- B.
Chemically combined in proportions that vary
- C.
Physically mixed in a fixed proportion
- D.
Physically mixed in proportions that vary
Correct Answer
A. Chemically combined in a fixed proportionExplanation
the molecule is chemically combined. The proportion is fixed, meaning two hydrogens and one oxygen.Rate this question:
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- 9.
The percent composition by mass of nitrogen in NH4OH (gram-formula mass = 35 grams/mole) is equal to
- A.
![Chem Aug 2010 Regents - Quiz]()
- B.
![Chem Aug 2010 Regents - Quiz]()
- C.
![Chem Aug 2010 Regents - Quiz]()
- D.
![Chem Aug 2010 Regents - Quiz]()
Correct Answer
B.Explanation
calculating percent composition is the mass of the part divided by the mass of the whole.
In this example, 14/35Rate this question:
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- 10.
Which Group 15 element exists as diatomic molecules at STP?
- A.
Phosphorus
- B.
Nitrogen
- C.
Bismuth
- D.
Arsenic
Correct Answer
B. NitrogenExplanation
HOFBrINClRate this question:
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- 11.
What is the total number of electrons shared in a double covalent bond?
- A.
1
- B.
2
- C.
3
- D.
4
Correct Answer
D. 4Explanation
one bond is two electrons...double bonds means 4 electrons.Rate this question:
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- 12.
Given the balanced equation representing a reaction: Br2 +energy→Br+Br Which statement describes the energy change and bonds in this reaction?
- A.
Energy is released as bonds are broken.
- B.
Energy is released as bonds are formed.
- C.
Energy is absorbed as bonds are broken.
- D.
Energy is absorbed as bonds are formed.
Correct Answer
C. Energy is absorbed as bonds are broken.Explanation
To break a bond, energy must be added. Br2 is diatomic and the bonds are broken. Energy must go in to make the bonds break.Rate this question:
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- 13.
Which substance can not be broken down by a chemical change?
- A.
Methane
- B.
Propanal
- C.
Tungsten
- D.
Water
Correct Answer
C. TungstenExplanation
Tungsten (W) is an element. elements cannot be broken down by a chemical change.Rate this question:
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- 14.
Object A at 40.°C and object B at 80.°C are placed in contact with each other. Which statement describes the heat flow between the objects?
- A.
Heat flows from object A to object B.
- B.
Heat flows from object B to object A.
- C.
Heat flows in both directions between the objects.
- D.
No heat flow occurs between the objects.
Correct Answer
B. Heat flows from object B to object A.Explanation
Heat flows from higher temperature to lower temperature.Rate this question:
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- 15.
Which unit can be used to express the concentration of a solution?
- A.
L/s
- B.
J/g
- C.
Ppm
- D.
KPa
Correct Answer
C. PpmExplanation
Table T shows the correct answer...ppm is parts per million.Rate this question:
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- 16.
Which formula represents a mixture?
- A.
C6H12O6 (l)
- B.
C6H12O6 (s)
- C.
LiCl (aq)
- D.
LiCl (s)
Correct Answer
C. LiCl (aq)Explanation
Process of elimination: (l) means liquid, (s) means solid, and (aq) means aqueous. AQUEOUS means dissolved in water. Dissolved in water is a mixture.Rate this question:
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- 17.
Which gas sample at STP has the same total number of molecules as 2.0 liters of CO2(g) at STP?
- A.
5.0 L of CO2(g)
- B.
2.0 L of Cl2(g)
- C.
3.0 L of H2S(g)
- D.
6.0 L of He(g)
Correct Answer
B. 2.0 L of Cl2(g)Explanation
All gases with the same volume have the same number of molecules, regardless of their molecular formula. In other words, 2.0 L of ANY gas has the same number of particles as 2.0 L of any other gas.Rate this question:
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- 18.
Petroleum can be separated by distillation because the hydrocarbons in petroleum are
- A.
Elements with identical boiling points
- B.
Elements with different boiling points
- C.
Compounds with identical boiling points
- D.
Compounds with different boiling points
Correct Answer
D. Compounds with different boiling pointsExplanation
The compounds have different boiling points, which is distillation.Rate this question:
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- 19.
Which sample has particles with the lowest average kinetic energy?
- A.
1.0 g of Br2 at 50.°C
- B.
2.0 g of Br2 at 30.°C
- C.
7.0 g of Br2 at 40.°C
- D.
9.0 g of Br2 at 20.°C
Correct Answer
D. 9.0 g of Br2 at 20.°CExplanation
Average kinetic energy is TEMPERATURE. The lowest temperature is 20C.Rate this question:
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- 20.
Which compound is insoluble in water?
- A.
KOH
- B.
NH4Cl
- C.
Na2SO4
- D.
PbSO4
Correct Answer
D. PbSO4Explanation
Group 1 elements are ALWAYS soluble. Ammonium (NH4) is ALWAYS soluble. Pb (lead) is an exception to the sulfate rule.Rate this question:
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- 21.
A gas sample is at 25°C and 1.0 atmosphere. Which changes in temperature and pressure will cause this sample to behave more like an ideal gas?
- A.
Decreased temperature and increased pressure
- B.
Decreased temperature and decreased pressure
- C.
Increased temperature and increased pressure
- D.
Increased temperature and decreased pressure
Correct Answer
D. Increased temperature and decreased pressureExplanation
HIGH temperature and LOW pressure is an ideal gas.Rate this question:
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- 22.
The isotopes K-37 and K-42 have the same
- A.
Decay mode
- B.
Bright-line spectrum
- C.
Mass number for their atoms
- D.
Total number of neutrons in their atoms
Correct Answer
B. Bright-line spectrumExplanation
Bright-line spectrum deals with electrons. Electrons are not different between two different isotopes.Rate this question:
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- 23.
Which element is present in all organic compounds?
- A.
Carbon
- B.
Hydrogen
- C.
Nitrogen
- D.
Oxygen
Correct Answer
A. CarbonExplanation
organic chemistry deals with carbon...think about the unit.Rate this question:
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- 24.
Each of four test tubes contains a different concentration of HCl(aq) at 25°C. A 1-gram cube of Zn is added to each test tube. In which test tube is the reaction occurring at the fastest rate?
- A.
![Chem Aug 2010 Regents - Quiz]()
- B.
![Chem Aug 2010 Regents - Quiz]()
- C.
![Chem Aug 2010 Regents - Quiz]()
- D.
![Chem Aug 2010 Regents - Quiz]()
Correct Answer
A.Explanation
Higher concentrations make a reaction go faster.Rate this question:
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- 25.
Which energy conversion occurs during the operation of an electrolytic cell?
- A.
Chemical energy to electrical energy
- B.
Electrical energy to chemical energy
- C.
Nuclear energy to electrical energy
- D.
Electrical energy to nuclear energy
Correct Answer
A. Chemical energy to electrical energyExplanation
Chemical energy exists in the electrodes (the aqueous solutions and the solid blocks) and it is converted to electrical energy.Rate this question:
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- 26.
Which compound is an Arrhenius acid?
- A.
CaO
- B.
HCl
- C.
NaOH
- D.
NH3
Correct Answer
B. HClExplanation
Arrhenius acid has H+ as the only positive ion in the solution.Rate this question:
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- 27.
Based on the results of testing colorless solutions with indicators, which solution is most acidic?
- A.
A solution in which bromthymol blue is blue
- B.
A solution in which bromcresol green is blue
- C.
A solution in which phenolphthalein is pink
- D.
A solution in which methyl orange is red
Correct Answer
D. A solution in which methyl orange is redExplanation
Methyl orange is red in acidic solutions.Rate this question:
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- 28.
According to one acid-base theory, water acts as an acid when an H2O molecule
- A.
Accepts an H+
- B.
Donates an H+
- C.
Accepts an H-
- D.
Donates an H-
Correct Answer
B. Donates an H+Explanation
Bronsted-Lowry acids donate H+.Rate this question:
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- 29.
In which type of reaction is an atom of one element converted to an atom of a different element?
- A.
Decomposition
- B.
Neutralization
- C.
Transmutation
- D.
Saponification
Correct Answer
C. TransmutationExplanation
transmutation is a nuclear reaction that converts one element to another element.Rate this question:
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- 30.
Which nuclide is listed with its half-life and decay mode?
- A.
K-37, 1.24 h, α
- B.
N-16, 7.2 s, β−
- C.
Rn-222, 1.6 × 10^3 y, α
- D.
U-235, 7.1 × 10^8 y, β−
Correct Answer
B. N-16, 7.2 s, β−Explanation
The only one that matches is the Nitrogen...look at Table N.Rate this question:
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- 31.
The table below shows the number of subatomic particles in atom X and in atom Z. Atom X and atom Z are isotopes of the element
- A.
Aluminum
- B.
Carbon
- C.
Magnesium
- D.
Nitrogen
Correct Answer
B. CarbonExplanation
6 protons equals carbon. 'NUFF SAID.Rate this question:
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- 32.
- The greatest composition by mass in an atom of oxygen-18 is due to the total mass of its
- A.
Electrons
- B.
Neutrons
- C.
Protons
- D.
Positrons
Correct Answer
B. NeutronsExplanation
oxygen-17 has 8 protons. oxygen-17 has 9 neutrons. More of the mass is from the neutrons.Rate this question:
- 33.
The bond between which two atoms is most polar?
- A.
Br and Cl
- B.
Br and F
- C.
I and Cl
- D.
I and F
Correct Answer
D. I and FExplanation
Iodine is the least electronegative of the Group 17 elements listed...Fluorine is the most electronegative of the Group 17 elements. The electronegativities of the two elements is the farthest apart, meaning the most polar.Rate this question:
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- 34.
In the formula X2(SO4)3, the X represents a metal. This metal could be located on the Periodic Table in
- A.
Group 1
- B.
Group 2
- C.
Group 13
- D.
Group 14
Correct Answer
C. Group 13Explanation
Group 13 has oxidation states of +3, SO4 has an oxidation of -2. Switch the numbers.Rate this question:
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- 35.
At STP, which element is solid, brittle, and a poor conductor of electricity?
- A.
Al
- B.
K
- C.
Ne
- D.
S
Correct Answer
D. SExplanation
Neon is a gas, so the answer cannot be Ne. Sulfur is a nonmetal, which makes it brittle.Rate this question:
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- 36.
Given the balanced equation representing a reaction: 2NaCl(l) → 2Na(l) + Cl2(g) A 1170.-gram sample of NaCl(l) completely reacts, producing 460. grams of Na(l). What is the total mass of Cl2(g) produced?
- A.
355 g
- B.
710 g
- C.
1420 g
- D.
1630 g
Correct Answer
B. 710 gExplanation
Do the math. 1170 - 460 = 710 g.Rate this question:
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- 37.
Given the formula representing a hydrocarbon: The molecular formula and the empirical formula for this hydrocarbon are
- A.
C5H10 and CH2
- B.
C5H10 and CH3
- C.
C4H8 and CH2
- D.
C4H8 and CH3
Correct Answer
A. C5H10 and CH2Explanation
the compound is for pentENE, and the formula is C5H10. The empirical formula (simplest form) is CH2.Rate this question:
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- 38.
Which element forms an ionic compound when it reacts with lithium?
- A.
K
- B.
Fe
- C.
Kr
- D.
Br
Correct Answer
D. BrExplanation
Kr is a noble gas, so it doesn't react. Br is a nonmetal and nonmetals form ionic bonds when reacted with metals.Rate this question:
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- 39.
Given the formula representing a molecule: The molecule is
- A.
Symmetrical and polar
- B.
Symmetrical and nonpolar
- C.
Asymetrical and polar
- D.
Asymmetrical and nonpolar
Correct Answer
B. Symmetrical and nonpolarExplanation
The molecule is symmetrical, which makes it nonpolar overall.Rate this question:
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- 40.
Which compound has both ionic and covalent bonds
- A.
CO2
- B.
CH3OH
- C.
NaI
- D.
Na2CO3
Correct Answer
D. Na2CO3Explanation
A compound with both ionic and covalent bonds would be one that has Table E compounds as well as a metal.Rate this question:
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- 41.
A cylinder with a movable piston contains a sample of gas having a volume of 6.0 liters at 293 K and 1.0 atmosphere. What is the volume of the sample after the gas is heated to 303 K, while the pressure is held at 1.0 atmosphere?
- A.
9.0 L
- B.
6.2 L
- C.
5.8 L
- D.
4.0 L
Correct Answer
B. 6.2 LExplanation
Combined gas law problems. Plug in the digits...6.2 L.Rate this question:
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- 42.
What is the minimum amount of heat required to completely melt 20.0 grams of ice at its melting point?
- A.
20.0 J
- B.
83.6 J
- C.
6680 J
- D.
45 200 J
Correct Answer
C. 6680 JExplanation
Using the heat of fusion (melting and freezing), you will multiply 20 by 334 to get 6680Rate this question:
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- 43.
As the temperature of a chemical reaction in the gas phase is increased, the rate of the reaction increases because
- A.
Fewer particle collisions occur
- B.
More effective particle collisions occur
- C.
The required activation energy increases
- D.
The concentration of the reactants increases
Correct Answer
B. More effective particle collisions occurExplanation
Higher temperatures means more effective collisions...Rate this question:
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- 44.
The entropy of a sample of CO2 increases as the CO2 changes from
- A.
Gas to liquid
- B.
Gas to solid
- C.
Liquid to solid
- D.
Solid to gas
Correct Answer
D. Solid to gasExplanation
Entropy is randomness, gases are the most random.Rate this question:
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- 45.
Which two factors must be equal when a chemical reaction reaches equilibrium?
- A.
The concentration of the reactants and the concentration of the products
- B.
The number of reactant particles and the number of product particles
- C.
The rate of the forward reaction and the rate of the reverse reaction
- D.
The mass of the reactants and the mass of the products
Correct Answer
C. The rate of the forward reaction and the rate of the reverse reactionExplanation
Rates of reactions in an equilibrium must be constant.Rate this question:
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- 46.
Which formula represents an unsaturated hydrocarbon?
- A.
C5H12
- B.
C6H14
- C.
C7H16
- D.
C8H14
Correct Answer
D. C8H14Explanation
3 of them are alkanes. One is an alkyne (C8H14), which makes is unsaturated.Rate this question:
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- 47.
The reaction between an organic acid and an alcohol produces
- A.
An aldehyde
- B.
A ketone
- C.
An ether
- D.
An ester
Correct Answer
D. An esterExplanation
The COOH and OH react to "pop off" a water (HOH) and leaves a -COO- (which is an ester).Rate this question:
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- 48.
Which balanced equation represents a redox reaction?
- A.
AgNO3(aq)+NaCl(aq)→AgCl(s)+NaNO3(aq)
- B.
H2CO3(aq) → H2O(l) + CO2(g)
- C.
NaOH(aq) + HCl(aq) → NaCl(aq) + H2O(l)
- D.
Mg(s) + 2HCl(aq) → MgCl2(aq) + H2(g)
Correct Answer
D. Mg(s) + 2HCl(aq) → MgCl2(aq) + H2(g)Explanation
QUICK TIP: Look for the elements (Mg and H2)...they have oxidation states of ZERO...one increases (Mg) and one decreases (H)...hence the oxidation/reduction.Rate this question:
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- 49.
A solution with a pH of 2.0 has a hydronium ion concentration ten times greater than a solution with a pH of
- A.
1.0
- B.
0.20
- C.
3.0
- D.
20.
Correct Answer
C. 3.0Explanation
2.0 is ten times greater than 3.0. As you go from a whole number to the next lowest (i.e., 3.0 to 2.0), the hydronium (H+ or H3O+) increases ten times...a pH of 4.0 vs. a pH of 2.0 is different by a factor of 100 times.Rate this question:
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- 50.
Which isotope is used to treat cancer?
- A.
C-14
- B.
U-238
- C.
Co-60
- D.
Pb-206
Correct Answer
C. Co-60Explanation
C-14 is used to date organic substances.
U-238 is used to date minerals (rocks).
Pb-206 is harmful (think lead paint).
That leaves cobalt.Rate this question:
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