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ave atomic mass

Total questions: 26

Worksheet time: 22mins

Name
Class
Date
1.

The atomic mass of an element is the ___.

a)

average of the mass number and the atomic number for the element

b)

weighted average of the masses of the isotopes of the element

c)

total mass of the isotopes of the element

d)

total number of subatomic particles in the nucleus

2.

The atomic mass of an element depends upon the ___.

a)

relative abundance of protons in that element

b)

mass and relative abundance of each isotope of that element

c)

mass of each isotope of that element

d)

mass of each electron in that element

3.

Chlorine has two naturally occurring isotopes, Cl-35 and Cl-37, The atomic mass of chlorine is 35.45. Which of these two isotopes of chlorine is more abundant?

a)

Cl-35

b)

Cl-37

c)

Cannot be determined from the information provided.

4.

An element has three isotopes. Given the abundances and relative masses, calculate the average atomic mass and determine (from the periodic table) which element it is.


Abundances | Relative masses

0.005% | 234.04 amu

0.720% | 235.04 amu

99.275% | 238.05 amu

a)

Uranium (#92, Atomic Mass: 238.03 amu)

b)

Fluorine (#9, Atomic Mass: 19.00 amu)

c)

Mercury (#89, Atomic Mass: 200.59 amu)

d)

Polonium (#84 209 amu)

5.

Rubidium has two naturally occurring isotopes, 85Rb (relative mass 84.9118 amu) and 87Rb (relative mass 86.9092 amu). The abundance of 87Rb is 27.8%, If rubidium has an average atomic mass of 85.47 amu, what is the % abundance of 85Rb (in percent)?

a)

27.9%

b)

72.1%

c)

74.63%

d)

34.29%

6.

Element Z has 2 natural isotopes. One isotope has a mass of 15.0 amu and a relative abundance of 30%. The other isotope has a mass of 16.0 amu and a relative abundance of 70%. Estimate the average atomic mass for this one element.

a)

15.0 amu

b)

16.0 amu

c)

15.7 amu

d)

16.9 amu

7.
4.35% of all X atoms have a mass of 39.946 amu. 83.79% have a mass of 41.941 amu, 9.50% have a mass of 42.941 amu, and 2.36% have a mass of 43.939 amu. What is the average atomic mass of atom X?
a)
41.97 amu
b)
42.19 amu
c)
10.43 amu
d)
40.04 amu
8.

Calculate the average atomic mass of silver.

a)

106.38649amu

b)

111.91896amu

c)

107.8677amu

d)

121

9.
Nitrogen has three occurring isotopes: Nitrogen-13, Nitrogen-14, Nitrogen-15. Which isotope is the most abundant?
a)
Nitrogen-13
b)
Nitrogen-14
c)
Nitrogen-15
d)
Based on the information given, it cannot be determined
10.
Four isotopes of lead include lead-204, lead-206, lead-207, and lead-208.  The average atomic mass of lead is 207.2.  Which isotope of lead is likely to be the most abundant.
a)
204
b)
206
c)
207
d)
208
11.

Rubidium has two common isotopes, 85Rb and 87Rb. If the abundance of 85Rb is 72.2% and the abundance of 87Rb is 27.8%, what is the average atomic mass of rubidium?

a)

85.468 amu

b)

37 amu

c)

85.6 amu

d)

86.4 amu

12.
What do the heights of the peaks represent in the mass spectrum?
a)
number of isotopes
b)
relative abundance of each isotope
c)
average atomic mass
d)
charge:mass ratio
13.
What do the peaks on the mass spectrum represent?
a)
anions
b)
different isotopes
c)
atoms with differing numbers of electrons
d)
numbers of electrons
14.

Calculate the average atomic mass from the mass spec.

a)

85.56 amu

b)

85.75 amu

c)

86.44 amu

d)

86.74

15.

What element has the following mass spec data?

a)

Sulfur

b)

Nitrogen

c)

Oxygen

d)

Carbon

16.

What element has the following mass spec data?

a)

Thulium

b)

Copper

c)

Europium

d)

Zinc

17.

How many isotopes are shown in this mass spec?

a)

1

b)

2

c)

6

d)

7

18.

Based on the mass spec data, which Iron isotope is the most abundant?

a)

Fe-54

b)

Fe-56

c)

Fe-57

d)

Fe-58

19.

What element has the following mass spec data?

a)

Tin

b)

Tellurium

c)

Chromium

d)

Polonium

20.

Use the mass spectrograph to calculate the weighted atomic mass of this sample.

a)

107

b)

107.89

c)

109

d)

109.97

21.

How many neutrons does an Oxygen-19 isotope have?

a)

19

b)

8

c)

11

d)

10

22.

How may electrons are in 3416S-2?

a)

18

b)

16

c)

14

d)

34

23.

How many protons does Phosphorus-30 have?

a)
30
b)
16
c)
12
d)
15
24.

What is the Nuclear Symbol for Uranium-238?

a)

23590Th

b)

23890Th

c)

23592U

d)

23892U

25.
The number of electrons in an atom of Mg-24 is 
a)
12
b)
14
c)
24
d)
none of those
26.

How may protons are in 3416S-2?

a)

18

b)

34

c)

16

d)

19