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Chem Aug 2010 Regents

50 Questions
Chem Aug 2010 Regents

Multiple choice + explanations.

Questions and Answers
  • 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

  • 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

  • 3. 
    In the late 1800s, experiments using cathode ray tubes led to the discovery of the 
    • A. 

      Electrons

    • B. 

      Neutrons

    • C. 

      Protons

    • D. 

      Positrons

  • 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

  • 5. 
    An atom of which element has the largest atomic radius? 
    • A. 

      Fe

    • B. 

      Mg

    • C. 

      Si

    • D. 

      Zn

  • 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

  • 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

  • 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

  • 9. 
    The percent composition by mass of nitrogen in NH4OH (gram-formula mass = 35 grams/mole) is equal to 
    • A. 
    • B. 
    • C. 
    • D. 
  • 10. 
    Which Group 15 element exists as diatomic molecules at STP? 
    • A. 

      Phosphorus

    • B. 

      Nitrogen

    • C. 

      Bismuth

    • D. 

      Arsenic

  • 11. 
    What is the total number of electrons shared in a double covalent bond? 
    • A. 

      1

    • B. 

      2

    • C. 

      3

    • D. 

      4

  • 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.

  • 13. 
    Which substance can not be broken down by a chemical change? 
    • A. 

      Methane

    • B. 

      Propanal

    • C. 

      Tungsten

    • D. 

      Water

  • 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.

  • 15. 
    Which unit can be used to express the concentration of a solution? 
    • A. 

      L/s

    • B. 

      J/g

    • C. 

      Ppm

    • D. 

      KPa

  • 16. 
    Which formula represents a mixture?
    • A. 

      C6H12O6 (l)

    • B. 

      C6H12O6 (s)

    • C. 

      LiCl (aq)

    • D. 

      LiCl (s)

  • 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)

  • 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

  • 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

  • 20. 
    Which compound is insoluble in water?    
    • A. 

      KOH

    • B. 

      NH4Cl

    • C. 

      Na2SO4

    • D. 

      PbSO4

  • 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

  • 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

  • 23. 
    Which element is present in all organic compounds? 
    • A. 

      Carbon

    • B. 

      Hydrogen

    • C. 

      Nitrogen

    • D. 

      Oxygen

  • 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. 
    • B. 
    • C. 
    • D. 
  • 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

  • 26. 
     Which compound is an Arrhenius acid?    
    • A. 

      CaO

    • B. 

      HCl

    • C. 

      NaOH

    • D. 

      NH3

  • 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

  • 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-

  • 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

  • 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−

  • 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

  • 32. 
    1. 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

  • 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

  • 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

  • 35. 
    At STP, which element is solid, brittle, and a poor conductor of electricity? 
    • A. 

      Al

    • B. 

      K

    • C. 

      Ne

    • D. 

      S

  • 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

  • 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

  • 38. 
    Which element forms an ionic compound when it reacts with lithium? 
    • A. 

      K

    • B. 

      Fe

    • C. 

      Kr

    • D. 

      Br

  • 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

  • 40. 
    Which compound has both ionic and covalent bonds
    • A. 

      CO2

    • B. 

      CH3OH

    • C. 

      NaI

    • D. 

      Na2CO3

  • 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

  • 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

  • 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

  • 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

  • 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

  • 46. 
    Which formula represents an unsaturated hydrocarbon? 
    • A. 

      C5H12

    • B. 

      C6H14

    • C. 

      C7H16

    • D. 

      C8H14

  • 47. 
    The reaction between an organic acid and an alcohol produces 
    • A. 

      An aldehyde

    • B. 

      A ketone

    • C. 

      An ether

    • D. 

      An ester

  • 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)

  • 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.

  • 50. 
    Which isotope is used to treat cancer?    
    • A. 

      C-14

    • B. 

      U-238

    • C. 

      Co-60

    • D. 

      Pb-206

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