Answer: Atom and Mass

CHEM131_S15_X1_Pract_Ans

Montgomery College
Takoma Park Silver Spring Campus
CHEM1 31 – Spring 2015

Name: _____Answers_____.

Exam I
Multiple Choice Questions: (3 points each = 30 points)
1) A graduated cylinder is filled with 25.0 mL of water. A solid sample is dropped into the graduated cylinder and the
3
water rises to the 37.6 mL mark. What is the mass of the solid if its density is 2.81 g/cm ?
A) 9.79 g

B) 106 g

C) 0.223 g

D) 70.3 g

E) 35.4 g

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2) A mass of methanol occupies 0.200 L. What volume would an equal mass of hexane occupy? The density of methanol is 0.792 g/mL and the density of hexane is 0.655 g/mL.
A) 104 mL
B) 242 mL
C) 192 mL
D) 125 mL
E) 229 mL

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3) The recommended adult dose of Elixophyllin , a drug used to treat asthma, is 15.0 mg/kg of body mass. Calculate the dose in milligrams for a 185-lb person. 1 lb = 453.6 g.
3
3
3
3
A) 9.58 x 10
B) 3.68 x 10
C) 2.78 x 10
D) 1.26 x 10
E) 5.59 × 10

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4) What species is represented by the following information? p+ = 17
2+

A) Ca

B) Ar

-

C) Cl

n° = 20 e- = 18
2-

D) Ca

E) S

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5) What mass in grams does 2.87 moles of sodium atoms have?
25
A) 1.39 x 10
B) 66.0
C) 8.01

D) 1.39 x 10

24

E) 1.73 x 10

24

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6) How many potassium atoms are contained in 15 g of potassium?
23
26
24
A) 2.3 × 10
B) 3.5 × 10
C) 9.0 × 10

D) 1.6 × 10

24

25

E) 3.3 × 10

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7) Calculate the mass percent composition of oxygen in C10H16O3.
A) 35 %
B) 17 %
C) 65 %

D) 8.7 %

E) 26 %

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8) Determine the