August 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 54-56 Questions 57-58 Questions 59-60 Questions 61-63 Questions 64-66 Questions 67-69 Questions 70-72 Questions 73-74 Questions 75-78 Questions 79-81

 

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Questions

AnswerExplanations
11 What is the total number of electrons shared in a double covalent bond?
(1) 1    (3) 3
(2) 2    (4) 4		4each bond has 2 electrons
12 Given the balanced equation representing a reaction:
Br2 + energy ==> Br + Br
Which statement describes the energy change and bonds in this reaction?
(1) Energy is released as bonds are broken.
(2) Energy is released as bonds are formed.
(3) Energy is absorbed as bonds are broken.
(4) Energy is absorbed as bonds are formed.		3energy is on the left so it is endothermic

atoms are no longer together so the bond is broken

13 Which substance can not be broken down by a chemical change?
(1) methane    (3) tungsten
(2) propanal   (4) water		3definition of an element
14 Object A at 40.C and object B at 80.C are placed in contact with each other. Which statement describes the heat flow between the objects?
(1) Heat flows from object A to object B.
(2) Heat flows from object B to object A.
(3) Heat flows in both directions between the objects.
(4) No heat flow occurs between the objects.		2heat flows from hot to cold
15 Which unit can be used to express the concentration of a solution?
(1) L/s   (3) ppm
(2) J/g    (4) kPa		3ppm,  or  mol/L is concentration  Table T, Table D
16 Which formula represents a mixture?
(1) C6H12O6(l)    (3) LiCl(aq)
(2) C6H12O6(s)   (4) LiCl(s)		3(aq) means it is dissolved in water
17 Which sample has particles with the lowest average kinetic energy?
(1) 1.0 g of I2 at 50.C
(2) 2.0 g of I2 at 30.C
(3) 7.0 g of I2 at 40.C
(4) 9.0 g of I2 at 20.C		4avg KE is temperature, pick the lowest temperature
18 Which gas sample at STP has the same total number of molecules as 2.0 liters of CO2(g) at STP?
(1) 5.0 L of CO2(g)  (3) 3.0 L of H2S(g)
(2) 2.0 L of Cl2(g)    (4) 6.0 L of He(g)		2Avogadro's Hypothesis Equal volumes of a gas at the same temperature and pressure contain equal numbers of molecules
19 Petroleum can be separated by distillation because the hydrocarbons in petroleum are
(1) elements with identical boiling points
(2) elements with different boiling points
(3) compounds with identical boiling points
(4) compounds with different boiling points		4distillation is based on boiling points
20 Which compound is insoluble in water?
(1) KOH     (3) Na3PO4
(2) NH4Cl   (4) PbSO4		4table F

Questions 1-10 Questions 11-20 Questions 21-30 Questions 31-40 Questions 41-50

Questions 51-53 Questions 54-56 Questions 57-58 Questions 59-60 Questions 61-63 Questions 64-66 Questions 67-69 Questions 70-72 Questions 73-74 Questions 75-78 Questions 79-81

 
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