August 2005 Chemistry Regents #41-50

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

 

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Questions

AnswerExplanations
41 What is the total number of moles of NaCl(s) needed to make 3.0 liters of a 2.0 M NaCl solution?
(1) 1.0 mol      (3) 6.0 mol
(2) 0.70 mol    (4) 8.0 mol		3M=mol/L  Table T

3.0L x 2.0M=

4nonmetal ion 8 valance electrons and a negative charge
43 A student wants to prepare a 1.0-liter solution of a specific Molarity. The student determines that the mass of the solute needs to be 30. grams. What is the proper procedure to follow?
(1) Add 30. g of solute to 1.0 L of solvent.
(2) Add 30. g of solute to 970. mL of solvent to make 1.0 L of solution.
(3) Add 1000. g of solvent to 30. g of solute.
(4) Add enough solvent to 30. g of solute to make 1.0 L of solution.		4see answer
44 What is the total number of joules released when a 5.00-gram sample of water changes from liquid to solid at 0°C?
(1) 334 J       (3) 2260 J
(2) 1670 J     (4) 11 300 J		2q=mHf

q=5 x 334

45 Which set of procedures and observations indicates a chemical change?
(1) Ethanol is added to an empty beaker and the ethanol eventually disappears.
(2) A solid is gently heated in a crucible and the solid slowly turns to liquid.
(3) Large crystals are crushed with a mortar and pestle and become powder.
(4) A cool, shiny metal is added to water in a beaker and rapid bubbling occurs.		4look for the obvious chemical reaction
46 At STP, a sample of which element has the highest entropy?
(1) Na(s)      (3) Br2(l)
(2) Hg(l)       (4) F2(g)		4gas has the highest entropy

solid lowest

47 Given the incomplete equation representing an organic addition reaction:
X(g) + Cl2(g)==> XCl2(g)
Which compound could be represented by X?
(1) CH     (3) C3H8
(2) C2H4   (4) C4H10		2addition=unsaturated (alkene or alkyne)

note the vowels hint hint

48 Given the incomplete equation:
4Fe + 3O2 ==> 2X
Which compound is represented by X?
(1) FeO       (3) Fe3O2
(2) Fe2O3   (4) Fe3O4		24Fe6O / 2= Fe2O3
49 How are HNO3(aq) and CH3COOH(aq) similar?
(1) They are Arrhenius acids and they turn blue litmus red.
(2) They are Arrhenius acids and they turn red litmus blue.
(3) They are Arrhenius bases and they turn blue litmus red.
(4) They are Arrhenius bases and they turn red litmus blue.		1both acids

use Table M

4alpha beta beta

use table O

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

 
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