Earth Science August 1999

Earth Science August 1999 Questions Answers Keys.

The University of the State of New York
REGENTS HIGH SCHOOL. EXAMINATION
CHEMISTRY
Thursday, August 12, 1999 -12:30 to 3:30 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. Which phase change represents sublimation?

(1) NFI₃(l) → NH₃(g)
(2) C0₂(s) → CO₂(g)
(3) KI(s) → KI(l)
(4) H₂0(l) → H₂0(s)

Answer: (2) C0₂(s) → CO₂(g)

2. The graph below shows the change in temperature of water in an open container as heat is added at a constant rate.

What is the pressure of the system at the temperature represented by segment DE?

(1) 0 torr
(2) betWeen O and 760 torr
(3) 760 torr
(4) more than 760 torr

Answer: (3) 760 torr

3. Winch subStance is a binary compound?

(1) potassium chlorite
(2) potassium chloride
(3) potassium hydroxide
(4) potassium cyanide

Answer: (2) potassium chloride

4. Which changes in pressure and temperature occur as a given mass of gas at 380 torr and 546 K is changed to STP?

(1) The pressure is doubled and the tempera—ture is halved.
(2) The pressure is halved and the temperatureiS dOubled.
(3) Both the pressure and the temperature are doubled.
(4) Both the pressure and the temperature are halved.

Answer: (1) The pressure is doubled and the tempera—ture is halved.

5. Real gas behavior deviates from ideal gas behavior because real gas particles have

(1) no volume and no attraction for each other
(2) no volume but some attraction for each other
(3) volume but no attraction for each other
(4) volume and some attraction for each other

Answer: (4) volume and some attraction for each other

6. Which type of radiation is most similar to high-energy x rays?

(1) alpha
(2) beta
(3) neutron
(4) gamma

Answer: (4) gamma/bg_collapse]

7. What is the total number of unpaired electrons in an atom of oxygen in the ground state?

(1) 6
(2) 2
(3) 8
(4) 4

Answer: (2) 2

8. Which of the following sublevels has the highest energy?

(1) 2p
(2) 2s
(3) 3p
(4) 3s

Answer: (3) 3p

9. In which pair of elements do the nuclei of the atoms contain the same number of neuirons?

Answer: (3)

10. Which reaction is matched correctly with the particle represented by letter X?

Answer: (1)

11. What is the maximum number of electrons in an orbital of any atom?

(1) 1
(2) 2
(3) 6
(4) 10

Answer: (2) 2

12. In which of the following elements is the least amount of energy required to remove the most loosely bound electron from an atom in the gaseous state?

(1) Sr
(2) Ar
(3) Al
(4) Cl

Answer: (1) Sr

13. What is the approximate total number of atoms in 1.0 mole of lithium?

(1) 1.0 x 10²³
(2) 6.0 x 10²³
(3) 3.0
(4) 6.9

Answer: (2) 6.0 x 10²³

14. The Potential chemical energy possessed by a substance is dependent on

(1) the composition of the substance, only
(2) the structure of the substance, only
(3) both the composition and structure of the substance
(4) neither the composition nor structure of the SubStanCe

Answer: (3) both the composition and structure of the substance

15. Between the molecules of which copound is hydrogen bonding strongest?

(1) HF
(2) HCl
(3) HBr
(4) HI

Answer: (1) HF

16. Which compound has a high melting point?

(1) SiO2
(2) CO2
(3) SO2
(4) NO2

Answer: (1) SiO2

17. Which structura1 formula represents a Polar molecule?

Answer: (4)

18. Which of the following elements has the greatest ability to attract electrons?

(1) Li
(2) Be
(3) Na
(4) Mg

Answer: (2) Be

19. The correct name of the compound with the for— mula PbO₂, is

(1) lead (I) oxide
(2) lead (II) oxide
(3) lead (III) oxide
(4) lead (IV) oXide

Answer: (4) lead (IV) oXide

20. Which element in Group 18 is naturally radioa ctive and has no stable isotopes?

(1) Ar
(2) Kr
(3) Xe
(4) Rn

Answer: (4) Rn

21. Which two elements have chemical properties that are most similar?

(1) Cl and Ar
(2) Li and na
(3) K and Ca
(4) C and N

Answer: (2) Li and na

22. Which list of elements contains two metalloids (semimetals)?

(1) Ga, Ge, Sn
(2) Si, P, S
(3) C, Si, Ge
(4) B, C, N

Answer: (3) C, Si, Ge

23 When a potassium atom reacts with bromine, the potassium atom will

(1) lose only 1 electron
(2) lose 2 electrons
(3) gain only 1 electron
(4) gain 2 electrons

Answer: (1) lose only 1 electron

24. If M represents an alkali metal, what is the formula for the compound formed by M and oxygen?

(1) MO₂
(2) M₂0
(3) M₂0₃
(4) M₃0₂

Answer: (2) M₂0

25. Properties of nonmetal atoms include

(1) low ionization energy and low electronega-tivity
(2) low ionization energy and high electronega-tivity
(3) high ionization energy and low electronega-tivitv
(4) high ionization energy and high electronega-tivitv

Answer: (4) high ionization energy and high electronega-tivitv

26. What is the total number of elements in Grot 17 that are gases at room temperature and sta dard pressure

(1) 1
(2) 2
(3) 3
(4) 4

Answer: (2) 2

27. What iS the gram formula mass of Ca(OH)₂?

(1) 29g
(2) 34 g
(3) 57g
(4) 74 g

Answer: (4) 74 g

28. What is the empirical formula fr C₃H₆?

(1) CH
(2) CH₂
(3) CH₃
(4) CH₆

Answer: (2) CH₂

29. What is the percent by mass of carbon in C0₂?

(1) 12
(2) 27
(3) 44
(4) 73

Answer: (2) 27

30. Given the reaction:

N₂(g) + 3H₂(g)→ 2NH₃(g)

What is the total number of moles of NII₃(g) produced when 10. moles of H₂(g) reacts completely with N₂(g)?

(1) 6.7
(2) 2.0
(3) 3.0
(4) 15

Answer: (1) 6.7

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