Chemistry 17 August 2016

Chemistry 17 August 2016 Questions Answer Keys

The University Of The State Of New York
Regents High School Examination
Physical Setting
Chemistry
Wednesday, August 17, 2016 — 8:30 to 11:30 a.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. Which change occurs when an atom in an excited state returns to the ground state?

(1) Energy is emitted.
(2) Energy is absorbed.
(3) The number of electrons decreases.
(4) The number of electrons increases.

Answer: (1) Energy is emitted.

2. The valence electrons in an atom of phosphorus in the ground state are all found in

(1) the first shell
(2) the second shell
(3) the third shell
(4) the fourth shell

Answer: (3) the third shell

3. Which two elements have the most similar chemical properties?

(1) beryllium and magnesium
(2) hydrogen and helium
(3) phosphorus and sulfur
(4) potassium and strontium

Answer: (1) beryllium and magnesium

4. Which phrase describes a compound that consists of two elements?

(1) a mixture in which the elements are in a variable proportion
(2) a mixture in which the elements are in a fixed proportion
(3) a substance in which the elements are chemically combined in a variable proportion
(4) a substance in which the elements are chemically combined in a fixed proportion

Answer: (4) a substance in which the elements are chemically combined in a fixed proportion

5. The formula mass of a compound is the

(1) sum of the atomic masses of its atoms
(2) sum of the atomic numbers of its atoms
(3) product of the atomic masses of its atoms
(4) product of the atomic numbers of its atoms

Answer: (1) sum of the atomic masses of its atoms

6. The arrangement of the elements from left to right in Period 4 on the Periodic Table is based on

(1) atomic mass
(2) atomic number
(3) the number of electron shells
(4) the number of oxidation states

Answer: (2) atomic number

7. Which diatomic molecule is formed when the two atoms share six electrons?

(1) H₂
(2) N₂
(3) O₂
(4) F₂

Answer: (2) N₂

8. Which formula represents a polar molecule?

(1) O₂
(2) CO₂
(3) NH₃
(4) CH₄

Answer: (3) NH₃

9. Which element is least likely to undergo a chemical reaction?

(1) lithium
(2) carbon
(3) fluorine
(4) neon

Answer: (4) neon

10. Which element has a melting point higher than the melting point of rhenium?

(1) iridium
(2) osmium
(3) tantalum
(4) tungsten

Answer: (4) tungsten

11. Which property can be defined as the ability of a substance to be hammered into thin sheets?

(1) conductivity
(2) malleability
(3) melting point
(4) solubility

Answer: (2) malleability

12. Which list of elements consists of a metal, a metalloid, and a noble gas?

(1) aluminum, sulfur, argon
(2) magnesium, sodium, sulfur
(3) sodium, silicon, argon
(4) silicon, phosphorus, chlorine

Answer: (3) sodium, silicon, argon

13. Which sample of matter has a crystal structure?

(1) Hg(ℓ)
(2) H₂O(ℓ)
(3) NaCl(s)
(4) CH₄(g)

Answer: (3) NaCl(s)

14. One mole of liquid water and one mole of solid water have different

(1) masses
(2) properties
(3) empirical formulas
(4) gram-formula masses

Answer: (2) properties

15. Which substance can not be broken down by a chemical change?

(1) butanal
(2) propene
(3) gold
(4) water

Answer: (3) gold

16. Which statement describes particles of an ideal gas, based on the kinetic molecular theory?

(1) Gas particles are separated by distances smaller than the size of the gas particles.
(2) Gas particles do not transfer energy to each other when they collide.
(3) Gas particles have no attractive forces between them.
(4) Gas particles move in predictable, circular motion.

Answer: (3) Gas particles have no attractive forces between them.

17. Which expression could represent the concentration of a solution?

(1) 3.5 g
(2) 3.5 M
(3) 3.5 mL
(4) 3.5 mol

Answer: (2) 3.5 M

18. Which form of energy is associated with the random motion of the particles in a sample of water?

(1) chemical energy
(2) electrical energy
(3) nuclear energy
(4) thermal energy

Answer: (4) thermal energy

19. Which change is most likely to occur when a molecule of H2 and a molecule of I2 collide with proper orientation and sufficient energy?

(1) a chemical change, because a compound is formed
(2) a chemical change, because an element is formed
(3) a physical change, because a compound is formed
(4) a physical change, because an element is formed

Answer: (1) a chemical change, because a compound is formed

20. Which changes can reach dynamic equilibrium?

(1) nuclear changes, only
(2) chemical changes, only
(3) nuclear and physical changes
(4) chemical and physical changes

Answer: (4) chemical and physical changes

21. What occurs when a reaction reaches equilibrium?

(1) The concentration of the reactants increases.
(2) The concentration of the products increases.
(3) The rate of the forward reaction is equal to the rate of the reverse reaction.
(4) The rate of the forward reaction is slower than the rate of the reverse reaction.

Answer: (3) The rate of the forward reaction is equal to the rate of the reverse reaction.

22. In terms of potential energy, PE, which expression defines the heat of reaction for a chemical change?

(1) PE _products – PE _reactants
(2) PE _{reactants –}PE _products

Answer: (1) PE _products – PE _reactants

23. Systems in nature tend to undergo changes that result in

(1) lower energy and lower entropy
(2) lower energy and higher entropy
(3) higher energy and lower entropy
(4) higher energy and higher entropy

Answer: (2) lower energy and higher entropy

24. What occurs when Cr³⁺ ions are reduced to Cr²⁺ ions?

(1) Electrons are lost and the oxidation number of chromium increases.
(2) Electrons are lost and the oxidation number of chromium decreases.
(3) Electrons are gained and the oxidation number of chromium increases.
(4) Electrons are gained and the oxidation number of chromium decreases.

Answer: (4) Electrons are gained and the oxidation number of chromium decreases.

25. Where do reduction and oxidation occur in an electrolytic cell?

(1) Both occur at the anode.
(2) Both occur at the cathode.
(3) Reduction occurs at the anode, and oxidation occurs at the cathode.
(4) Reduction occurs at the cathode, and oxidation occurs at the anode.

Answer: (4) Reduction occurs at the cathode, and oxidation occurs at the anode.

26. Which compound is an electrolyte?

(1) H₂O
(2) C₂H₆
(3) H₃PO₄
(4) CH₃OH

Answer: (3) H₃PO₄

27. When the hydronium ion concentration of an aqueous solution is increased by a factor of 10, the pH value of the solution

(1) decreases by 1
(2) increases by 1
(3) decreases by 10
(4) increases by 10

Answer: (1) decreases by 1

28. The stability of isotopes is related to the ratio of which particles in the atoms?

(1) electrons and protons
(2) electrons and positrons
(3) neutrons and protons
(4) neutrons and positrons

Answer: (3) neutrons and protons

29. Which radioisotope has the fastest rate of decay?

(1) ¹⁴C
(2) ³⁷Ca
(3) ⁵³Fe
(4) ⁴²K

Answer: (2) ³⁷Ca

30. The atomic mass of an element is the weighted average of the atomic masses of

(1) the least abundant isotopes of the element
(2) the naturally occurring isotopes of the element
(3) the artificially produced isotopes of the element
(4) the natural and artificial isotopes of the element

Answer: (2) the naturally occurring isotopes of the element

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