Chapter 18:
Properties of the Atom and the Periodic Table
Practice Test
1.
How many neutrons are in an atom of phosphorus-31?
a.
15
b.
16
c.
46
d.
31
Hint
2.
What is the ratio of neutrons to protons in the isotope radium-234?
a.
0.60
b.
1.66
c.
2.34
d.
1.00
Hint
3.
A magnesium atom has 12 protons and 12 neutrons. What is its mass number?
a.
12
b.
24
c.
1
d.
36
Hint
4.
Boron has a mass number of 11 and an atomic number of 5. How many neutrons are in a boron atom?
a.
6
b.
11
c.
16
d.
5
Hint
5.
The half-life of the radioactive isotope rubidium-87 is 48,800,000,000 years. Express this half-life in scientific notation.
a.
4.88 × 10
10
years
b.
488 × 10
8
years
c.
488 × 10
-8
years
d.
48,800 × 10
6
years
Hint
6.
Iodine-127 has a mass number of 127 and 74 neutrons. What percentage of the particles in an iodine-127 nucleus are protons?
a.
100%
b.
58%
c.
0%
d.
42%
Hint
7.
The radioactive isotope nickel-63 has a half life of 100 years. How much of a 10.0 g sample of nickel-63 is left after 300 years?
a.
5 g
b.
1.25 g
c.
2.5 g
d.
3.3 g
Hint
8.
About 80% of all magnesium atoms are magnesium-24, about 10% are magnesium-25, and about 10% are magnesium-26. What is the average atomic mass of magnesium?
a.
24.3 amu
b.
19.2 amu
c.
25.0 amu
d.
24.0 amu
Hint
9.
A neutral phosphorus atom has 15 electrons. How many electrons are in the third energy level?
a.
2
b.
8
c.
5
d.
15
Hint
10.
A sample of the radioactive isotope cobalt-62 is prepared. The sample has a mass of 1.00 g. After 3.0 minutes, the mass of cobalt-62 remaining is 0.25 g. What is the half-life of cobalt-62?
a.
1.5 minutes
b.
0.75 minutes
c.
1.0 minutes
d.
3.0 minutes
Hint
