Regents Chemistry Exam Explanations June 2010

June 2010 Chemistry Regents #11-20

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Questions 1-10 Questions 11-20 Questions 21-30 Questions 31-40 Questions 41-50
Questions 51-53 Questions 54-55 Questions 56-58 Questions 59-61 Questions 62-64 Questions 65-68 Questions 69-71 Questions 72-75 Questions 76-79 Questions 80-83

Questions
Answer Explanations
11 Which type of bond is found between atoms of solid cobalt?
(1) nonpolar covalent    (3) metallic
(2) polar covalent         (4) ionic 3 Cobalt is a metal so Metallic
12 Which equation represents sublimation?
(1) I_2(s) ==> I_2(g)    (3) I_2(l)==>I_2(g)
(2) I_2(s) ==>I_2(l)      (4) I_2(l)==>I_2(s) 1 solid to a gas
13 Which sample of ethanol has particles with the highest average kinetic energy?
(1) 10.0 mL of ethanol at 25°C
(2) 10.0 mL of ethanol at 55°C
(3) 100.0 mL of ethanol at 35°C
(4) 100.0 mL of ethanol at 45°C 2 the highest temperature = (avg. KE)
14 The molarity of an aqueous solution of NaCl is defined as the
(1) grams of NaCl per liter of water
(2) grams of NaCl per liter of solution
(3) moles of NaCl per liter of water
(4) moles of NaCl per liter of solution 4 Table T look it up
15 A real gas behaves least like an ideal gas under the conditions of
(1) low temperature and low pressure
(2) low temperature and high pressure
(3) high temperature and low pressure
(4) high temperature and high pressure 2 ideal conditions are like ideal vacations high temperature and low pressure
16 Which sample of matter can be separated into different substances by physical means?
(1) LiCl_(aq)    (3) NH_3(g)
(2) LiCl_(s)     (4) NH_3(l) 1 (aq) is a homogeneous mixture of a substance and water
17 At STP, 1.0 liter of helium contains the same total number of atoms as
(1) 1.0 L of Ne   (3) 0.5 L of Rn
(2) 2.0 L of Kr    (4) 1.5 L of Ar 1 Avogadros Hypothesis- same volume under the same conditions of temp and pressure have the same # of molecules
18 Which statement describes the particles of an ideal gas?
(1) The particles move in well-defined, circular paths.
(2) When the particles collide, energy is lost.
(3) There are forces of attraction between the particles.
(4) The volume of the particles is negligible. 4 ideal gases never can form liquids so the volume is non existent or at low temps is would appear as a drop
19 A chemical reaction between iron atoms and oxygen molecules can only occur if
(1) the particles are heated
(2) the atmospheric pressure decreases
(3) there is a catalyst present
(4) there are effective collisions between the particles 4 definition of a reaction= effective collisions
20 Given the equation representing a phase change at equilibrium:
H₂O_(s) <==>H₂O_(l)
Which statement describes this equilibrium?
(1) The H₂O_(s) melts faster than the H₂O_(l) freezes.
(2) The H₂O_(l) freezes faster than the H₂O_(s) melts.
(3) The mass of H₂O_(s) must equal the mass of H₂O_(l).
(4) The mass of H₂O_(l) and the mass of H₂O_(s) each remain constant. 4 equilibrium "con con requal"
rates are equal in both directions
the amount of each therefore remains the same
Questions 1-10 Questions 11-20 Questions 21-30 Questions 31-40 Questions 41-50
Questions 51-53 Questions 54-55 Questions 56-58 Questions 59-61 Questions 62-64 Questions 65-68 Questions 69-71 Questions 72-75 Questions 76-79 Questions 80-83

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Questions	Answer	Explanations
11 Which type of bond is found between atoms of solid cobalt? (1) nonpolar covalent (3) metallic (2) polar covalent (4) ionic	3	Cobalt is a metal so Metallic
12 Which equation represents sublimation? (1) I_2(s) ==> I_2(g) (3) I_2(l)==>I_2(g) (2) I_2(s) ==>I_2(l) (4) I_2(l)==>I_2(s)	1	solid to a gas
13 Which sample of ethanol has particles with the highest average kinetic energy? (1) 10.0 mL of ethanol at 25°C (2) 10.0 mL of ethanol at 55°C (3) 100.0 mL of ethanol at 35°C (4) 100.0 mL of ethanol at 45°C	2	the highest temperature = (avg. KE)
14 The molarity of an aqueous solution of NaCl is defined as the (1) grams of NaCl per liter of water (2) grams of NaCl per liter of solution (3) moles of NaCl per liter of water (4) moles of NaCl per liter of solution	4	Table T look it up
15 A real gas behaves least like an ideal gas under the conditions of (1) low temperature and low pressure (2) low temperature and high pressure (3) high temperature and low pressure (4) high temperature and high pressure	2	ideal conditions are like ideal vacations high temperature and low pressure
16 Which sample of matter can be separated into different substances by physical means? (1) LiCl_(aq) (3) NH_3(g) (2) LiCl_(s) (4) NH_3(l)	1	(aq) is a homogeneous mixture of a substance and water
17 At STP, 1.0 liter of helium contains the same total number of atoms as (1) 1.0 L of Ne (3) 0.5 L of Rn (2) 2.0 L of Kr (4) 1.5 L of Ar	1	Avogadros Hypothesis- same volume under the same conditions of temp and pressure have the same # of molecules
18 Which statement describes the particles of an ideal gas? (1) The particles move in well-defined, circular paths. (2) When the particles collide, energy is lost. (3) There are forces of attraction between the particles. (4) The volume of the particles is negligible.	4	ideal gases never can form liquids so the volume is non existent or at low temps is would appear as a drop
19 A chemical reaction between iron atoms and oxygen molecules can only occur if (1) the particles are heated (2) the atmospheric pressure decreases (3) there is a catalyst present (4) there are effective collisions between the particles	4	definition of a reaction= effective collisions
20 Given the equation representing a phase change at equilibrium: H₂O_(s) <==>H₂O_(l) Which statement describes this equilibrium? (1) The H₂O_(s) melts faster than the H₂O_(l) freezes. (2) The H₂O_(l) freezes faster than the H₂O_(s) melts. (3) The mass of H₂O_(s) must equal the mass of H₂O_(l). (4) The mass of H₂O_(l) and the mass of H₂O_(s) each remain constant.	4	equilibrium "con con requal" rates are equal in both directions the amount of each therefore remains the same