June 2002 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

Answer Explanations
41 The gram formula mass of NH4Cl is


(1) 22.4 g/mole     (3) 53.5 g/mole
(2) 28.0 g/mole     (4) 95.5 g/mole

3 NH4Cl=53.5g/mol

N=14

H= 4(1)=4

Cl=35.5

42 What is the molarity of a solution that contains 0.50 mole of NaOH in
0.50 liter of solution?

(1) 1.0 M      (3) 0.25 M
(2) 2.0 M      (4) 0.50 M

 

1

M=

0.50moles
0.50 Liters
2 1-compound

2-mixture of elements

3-element

4-diatomic element

44 Which process is accompanied by a decrease in entropy?

(1) boiling of water
(2) condensing of water vapor
(3) subliming of iodine
(4) melting of ice

 

2         
     S  L G
1            L------>G
2            L<------G
3   S------------>G
4   S--->L

 

45 If 5.0 milliliters of a 0.20 M HCl solution is required to neutralize exactly
10. milliliters of NaOH, what is the concentration of the base?

(1) 0.10 M     (3) 0.30 M
(2) 0.20 M     (4) 0.40 M

1
Ma Va = Mb Vb
0.20M 5.0mL = M 10mL
46 Exactly how much time must elapse before 16 grams of potassium-42
decays, leaving 2 grams of the original isotope?

(1) 8 12.4 hours       (3) 3 12.4 hours
(2) 2 12.4 hours       (4) 4 12.4 hours

3 16->8->4->3 

= 3 (1/2 lives) x12.4h

47 Which mass measurement contains four significant figures?

(1) 0.086g    (3) 1003g
(2)  0.431g   (4) 3870g

3
0.086g   2 SF
0.431g 3 SF
1003g 4 SF
3870g 3 SF
48 Which pair of compounds are alcohols?

1 Look for -OH and no other functional groups
49 The process of joining many small molecules into larger molecules is called

(1) neutralization       (3) saponification
(2) polymerization     (4) substitution

 

2 Definition-polymerization

50 The diagram below represents a portion of a 100-milliliter graduated cylinder.

What is the reading of the meniscus?

(1) 35.0 mL    (3) 44.0 mL
(2) 36.0 mL    (4) 45.0 mL

 

1 estimate the last decimal place

 

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