Earth Science June 1999

Earth Science June 1999 Questions Answers Keys.

The University of the State of New York
REGENTS HIGH SCHOOL. EXAMINATION
CHEMISTRY
Friday, June 18, 1999 -1:15 to 4:15 p.m., only

Directions : For each statement or question, select the word or expression that, of those given, best completes the statement or answers the question. Record your answer on the separate answer sheet in accordance with the directions on the front page of this booklet.

1. Solid A at 80°C is immersed in liquid B at 60°C. Which statement correctly describes the energy changes between A and B?

  • (1) A releases heat and B absorbs heat.
  • (2) A absorbs heat and B releases heat.
  • (3) Both A and B absorb heat.
  • (4) Both A and B release heat.
Answer: (1) A releases heat and B absorbs heat. 

2. Given the phase equilibrium at a pressure of 1 atmosphere:

H20(s) ↔ H20(l)

What is the temperature of the equilibrium mixture?

  • (1) 273°C
  • (2) 273 K
  • (3) 373°C
  • (4) 373 K
Answer: (2) 273 K 

3. Which statement is an identifying characteristic of a mixture?

  • (1) A mixture can consist of a single element.
  • (2) A mixture can be separated by physical means.
  • (3) A mixture must have a definite composition by weight.
  • (4) A mixture must be homogeneous.
Answer: (2) A mixture can be separated by physical means. 

4. Which phase change is endothermic?

  • (1) gas → solid
  • (2) gas → liquid
  • (3) liquid → solid
  • (4) liquid → gas
Answer: (4) liquid → gas 

5. What volume will a 300.-milliliter sample of a gas at STP occupy when the pressure is doubled at constant temperature?

  • (1) 150. mL
  • (2) 450. mL
  • (3) 300. mL
  • (4) 600. mL
Answer: (1) 150. mL 

6. Each stoppered flask below contains 2 liters of a gas at STP.

Each gas sample has the same

  • (1) density
  • (2) mass
  • (3) number of molecules
  • (4) number of atoms
Answer: (3) number of molecules 

7. Which electron configuration represents an atom in the excited state?

  • (1) 1s22s22p63s2
  • (2) 1s22s22p63s1
  • (3) 1s22s22p6
  • (4) 1s22s22p53s2
Answer: (4) 1s22s22p53s2 

8. Which electron-dot symbol represents an atom of chlorine in the ground state?

Answer: (4)  

9. What is the total number of electrons in an atom of an element with an atomic number of 18 and a mass number of 40?

  • (1) 18
  • (2) 22
  • (3) 40
  • (4) 58
Answer: (1) 18 

10. After bombarding a gold foil sheet with alpha particles, scientists concluded that atoms consist mainly of

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

11. Which element has atoms in the ground state with a sublevel that is only half filled?

  • (1) helium
  • (2) beryllium
  • (3) nitrogen
  • (4) neon
Answer: (3) nitrogen 

12. Which sublevel contains a total of 5 orbitals?

  • (1) s
  • (2) p
  • (3) d
  • (4) f
Answer: (3) d 
  • (1) 8.0
  • (2) 16
  • (3) 20.
  • (4) 24
Answer: (4) 24 

14. Electronegativity is a measure of an atom’s ability to

  • (1) attract the electrons in the bond between the atom and another atom
  • (2) repel the electrons in the bond between the atom and another atom
  • (3) attract the protons of another atom
  • (4) repel the protons of another atom
Answer: (1) attract the electrons in the bond between the atom and another atom 

15. The molecular formula of a compound is represented by X3Y6. What is the empirical formula of this compound?

  • (1) X3Y
  • (2) X2Y
  • (3) xy2
  • (4) XY3
Answer: (3) xy2 

16. Given the unbalanced equation:

_CaSO4 + _AlCl3 → _ Al2(S04)3 + _CaCl2

What is the coefficient of Al2(S04)3 when the equation is completelY balanced using the smallest whole-number coefficients?

  • (1) 1
  • (2) 2
  • (3) 3
  • (4) 4
Answer: (1) 1 

17. What is the total number of moles of sulfur atoms in I mole of Fe2(S04)3?

  • (1) 1
  • (2) 15
  • (3) 3
  • (4) 17
Answer: (3) 3 

18. The elements Li and F combine to form an ionic compound. The electron configurations in this compound are the same as the electron configurations of atoms in Group

  • (1) 1
  • (2) 14
  • (3) 17
  • (4) 18
Answer: (4) 18 

19. An element with an elcetronegativity of 0.9 bonds with an element with an electronegativfty of 3.1. Which phrase best describes the bond between these elements?

  • (1) mostly ionic in character and formed between two nonmetals
  • (2) mostly ionic in character and formed between a metal and a nonmetal
  • (3) mostly covalent in character and formed between two nonmetals
  • (4) mostly covalent in character and formed between a metal and a nonmetal
Answer: (2) mostly ionic in character and formed between a metal and a nonmetal 

20. The symmetrical structure of the CH4 molecule is due to the fact that the four single bonds between carbon and hydrogen atoms are directed toward the corners of a

  • (1) triangle
  • (2) tetrahedron
  • (3) square
  • (4) rectangle
Answer: (2) tetrahedron 

21. As the elements in Group 15 are considered in order of increasing atomic number, which sequence in properties occurs?

  • (1) nonmetal → metalloid → metal
  • (2) metalloid → metal → nonmetal
  • (3) metal → metalloid → nonmetal
  • (4) metal → nonmetal → metallOid
Answer: (1) nonmetal → metalloid → metal 

22. In which set do the elements exhibit the most similar chemical properties?

  • (1) N, 0, and F
  • (2) Hg, Br, and Rn
  • (3) Li, Na, and K
  • (4) Al, Si, and P
Answer: (3) Li, Na, and K 

23. Which reactant is most likely to have d electrons involved in a chemical reaction?

  • (1) a halogen
  • (2) a noble gas
  • (3) a transition element
  • (4) an alkali metal
Answer: (3) a transition element 

24. Elements in a given period of the Periodic Table contain the same number of

  • (1) protons in the nucleus
  • (2) neutrons in the nucleus
  • (3) electrons in the outermost level
  • (4) occupied principal energy levels
Answer: (4) occupied principal energy levels 

25. The elements known as the alkaline earth metals are found in Group

  • (1) 1
  • (2) 2
  • (3) 16
  • (4) 17
Answer: (2) 2 

26. The properties of silicon are characteristic of

  • (1) a metal, only
  • (2) a nonmetal, only
  • (3) both a metal and a nonmetal
  • (4) neither a metal nor a nonmetal
Answer: (3) both a metal and a nonmetal 

27. Which substance has the greatest molecular mass?

  • (1) H2O2
  • (2) NO
  • (3) CF4
  • (4) l2
Answer: (4) l2 

28. According to Reference Table D, which of the following substances is least soluble in 100 grams of water at 50°C?

  • (1) NaCl
  • (2) KCl
  • (3) NH4Cl
  • (4) HCl
Answer: (1) NaCl 

29. Which sample contains a total of 6.0 x 1023 atoms?

  • (1) 23gNa
  • (2) 24gC
  • (3) 42gKr
  • (4) 78gK
Answer: (1) 23gNa 

30. A 20.-milliliter sample of 0.60 M HCl is diluted with water to a volume of 40. milliliters. What is the new concentration of the solution?

  • (1) 0.15 M
  • (2) 0.60 M
  • (3) 0.30 M
  • (4) 1.2 M
Answer: (3) 0.30 M 

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