Chemistry 28 January 2015

Chemistry 28 January 2015 Questions Answer Keys

The University Of The State Of New York
Regents High School Examination
Physical Setting
Chemistry
Wednesday, January 28, 2015 — 1:15 to 4:15 p.m., only

Directions (1–30): For each statement or question, record on your separate answer sheet the number of the word or expression that, of those given, best completes the statement or answers the question. Some questions may require the use of the 2011 Edition Reference Tables for Physical Setting/Chemistry.

1. According to the modern model of the atom, the nucleus of an atom is surrounded by one or more

  • (1) electrons
  • (2) neutrons
  • (3) positrons
  • (4) protons
Answer: (1) electrons 

2. Which particle has a mass of approximately 1 atomic mass unit?

  • (1) an alpha particle
  • (2) a beta particle
  • (3) an electron
  • (4) a neutron
Answer: (4) a neutron 

3. A specific amount of energy is emitted when excited electrons in an atom in a sample of an element return to the ground state. This emitted energy can be used to determine the

  • (1) mass of the sample
  • (2) volume of the sample
  • (3) identity of the element
  • (4) number of moles of the element
Answer: (3) identity of the element 

4. According to the wave-mechanical model, an orbital is defined as the

  • (1) circular path for electrons
  • (2) circular path for neutrons
  • (3) most probable location of electrons
  • (4) most probable location of neutrons
Answer: (3) most probable location of electrons 

5. All phosphorus atoms have the same

  • (1) atomic number
  • (2) mass number
  • (3) number of neutrons plus the number of electrons
  • (4) number of neutrons plus the number of protons
Answer: (1) atomic number 

6. At STP, which element is a good conductor of electricity?

  • (1) chlorine
  • (2) iodine
  • (3) silver
  • (4) sulfur
Answer: (3) silver 

7. Which phrase describes the molecular structure and properties of two solid forms of carbon, diamond and graphite?

  • (1) the same molecular structures and the same properties
  • (2) the same molecular structures and different properties
  • (3) different molecular structures and the same properties
  • (4) different molecular structures and different properties
Answer: (4) different molecular structures and different properties 

8. Which quantity is equal to one mole of Au?

  • (1) the atomic mass in grams
  • (2) the atomic number in grams
  • (3) the mass of neutrons in grams
  • (4) the number of neutrons in grams
Answer: (1) the atomic mass in grams 

9. Given the balanced equation representing the reaction between methane and oxygen:

CH4 + 2O2 → CO2 + 2H2O

According to this equation, what is the mole ratio of oxygen to methane?

Chemistry 28 January 2015
Answer: (4)

10. Which list includes three types of chemical reactions?

  • (1) decomposition, single replacement, and solidification
  • (2) decomposition, single replacement, and double replacement
  • (3) solidification, double replacement, and decomposition
  • (4) solidification, double replacement, and single replacement
Answer: (2) decomposition, single replacement, and double replacement

11. Which compound has the greatest percent composition by mass of sulfur?

  • (1) BaS
  • (2) CaS
  • (3) MgS
  • (4) SrS
Answer: (3) MgS

12. Two molecules of HBr collide and then form H2 and Br2. During the collision, the bonds in the HBr molecules are

  • (1) broken as energy is absorbed
  • (2) broken as energy is released
  • (3) formed as energy is absorbed
  • (4) formed as energy is released
Answer: (1) broken as energy is absorbed

13. Which atom in the ground state has a stable electron configuration?

  • (1) carbon
  • (2) magnesium
  • (3) neon
  • (4) oxygen
Answer: (3) neon

14. Which statement describes a multiple covalent bond?

  • (1) Two electrons are shared.
  • (2) Four electrons are shared.
  • (3) Two electrons are transferred.
  • (4) Four electrons are transferred.
Answer: (2) Four electrons are shared.

15. The electronegativity difference between the atoms in a molecule of HCl can be used to determine

  • (1) the entropy of the atoms
  • (2) the atomic number of the atoms
  • (3) the first ionization energy of the atoms
  • (4) the polarity of the bond between the two atoms
Answer: (4) the polarity of the bond between the two atoms

16. Which two gases can not be broken down by chemical means?

  • (1) CO and He
  • (2) CO and NH3
  • (3) Xe and He
  • (4) Xe and NH3
Answer: (3) Xe and He

17. Two substances in a mixture differ in density and particle size. These properties can be used to

  • (1) separate the substances
  • (2) chemically combine the substances
  • (3) determine the freezing point of the mixture
  • (4) predict the electrical conductivity of the mixture
Answer: (1) separate the substances

18. Which unit is used to express an amount of thermal energy?

  • (1) gram
  • (2) mole
  • (3) joule
  • (4) pascal
Answer: (3) joule

19. Under which conditions of temperature and pressure does a real gas behave most like an ideal gas?

  • (1) low temperature and low pressure
  • (2) low temperature and high pressure
  • (3) high temperature and low pressure
  • (4) high temperature and high pressure
Answer: (3) high temperature and low pressure

20. According to the kinetic molecular theory for an ideal gas, all gas particles

  • (1) are in random, constant, straight-line motion
  • (2) are separated by very small distances relative to their sizes
  • (3) have strong intermolecular forces
  • (4) have collisions that decrease the total energy of the system
Answer: (1) are in random, constant, straight-line motion

21. Which mathematical expression represents the heat of reaction for a chemical reaction?

  • (1) (the heat of fusion) – (the heat of vaporization)
  • (2) (the heat of vaporization) – (the heat of fusion)
  • (3) (the potential energy of the products) – (the potential energy of the reactants)
  • (4) (the potential energy of the reactants) – (the potential energy of the products)
Answer: (3) (the potential energy of the products) – (the potential energy of the reactants)

22. At 101.3 kPa and 298 K, a 1.0-mole sample of which compound absorbs the greatest amount of heat as the entire sample dissolves in water?

  • (1) LiBr
  • (2) NaCl
  • (3) NaOH
  • (4) NH4Cl
Answer: (4) NH4Cl 

23. For a reaction at equilibrium, which change can increase the rates of the forward and reverse reactions?

  • (1) a decrease in the concentration of the reactants
  • (2) a decrease in the surface area of the products
  • (3) an increase in the temperature of the system
  • (4) an increase in the activation energy of the forward reaction
Answer: (3) an increase in the temperature of the system 

24. Which reaction produces ethanol?

  • (1) combustion
  • (2) esterification
  • (3) fermentation
  • (4) polymerization
Answer: (3) fermentation

25. The chemical process in which electrons are gained by an atom or an ion is called

  • (1) addition
  • (2) oxidation
  • (3) reduction
  • (4) substitution
Answer: (3) reduction

26. Which process occurs in an operating voltaic cell?

  • (1) Electrical energy is converted to chemical energy.
  • (2) Chemical energy is converted to electrical energy.
  • (3) Oxidation takes place at the cathode.
  • (4) Reduction takes place at the anode.
Answer: (2) Chemical energy is converted to electrical energy.

27. What can be explained by the Arrhenius theory?

  • (1) the behavior of many acids and bases
  • (2) the effect of stress on a phase equilibrium
  • (3) the operation of an electrochemical cell
  • (4) the spontaneous decay of some nuclei
Answer: (1) the behavior of many acids and bases

28. According to one acid-base theory, a water molecule acts as an acid when the molecule

  • (1) donates an H+ ion
  • (2) accepts an H+ ion
  • (3) donates an OH ion
  • (4) accepts an OH ion
Answer: (1) donates an H+ ion

29. Positrons and beta particles have

  • (1) the same charge and the same mass
  • (2) the same charge and different masses
  • (3) different charges and the same mass
  • (4) different charges and different masses
Answer: (3) different charges and the same mass 

30. Which term identifies a type of nuclear reaction?

  • (1) transmutation
  • (2) neutralization
  • (3) deposition
  • (4) reduction
Answer: (1) transmutation

 

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