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Half-life & Isotopes Review

Total questions: 76

Worksheet time: 5hrs 23mins

Name
Class
Date
1.

After 22,800 years, approximately what percentage of the original carbon-14 remains?

a)

15%

b)

12.5%

c)

6.25%

d)

3.125%

2.
What is the half-life of iodine-131?
a)
32 days
b)
8 days
c)
16 days
d)
24 days
3.

The % of the parent isotope remaining after 1 Half Life.

a)

50%

b)

25%

c)

12.5%

d)

6.25%

4.

The % of the parent isotope remaining after 2 Half Lives.

a)

50%

b)

25%

c)

12.5%

d)

6.25%

5.

What is the Half life of this isotope?

a)

5 seconds

b)

10 seconds

c)

15 seconds

d)

20 seconds

6.

What is the Half Life of this isotope?

a)

3 days

b)

5 days

c)

8 days

d)

10 days

7.
What is Half-life?
a)
The amount of time it takes for some of the nuclei in a sample of the isotope to decay
b)
The amount of time it takes for half the electrons in a sample of the isotope to decay
c)
The amount of time it takes for half the nuclei in a sample of the isotope to decay
d)
the amount of time it takes to double the nuclei in a sample of the isotope to decay
8.
If one-fourth of the carbon-14 is remaining then how many half-lives have passed?
a)
1
b)
2
c)
3
d)
4
9.

Why do some elements have half-lives?

a)

they radioactively decay

b)

half of their atom gets stolen

c)

They are Twizzlers that break in half

10.

What is the only difference between two different isotopes of the same element?

a)

Number of neutrons

b)

Number of protons

c)

Number of electrons

d)

Size of atom

11.

The half-life of Element X is 2 years.


How long has passed if Element X has reduced by half 5 times?

a)

2 years

b)

4 years

c)

6 years

d)

8 years

e)

10 years

12.

After the third half-life, how much of the sample is left?

a)

1/2

b)

1/3

c)

1/16

d)

1/8

13.

Half life (in radioactivity) is the amount of time it takes for half of a radioactive sample to

a)

split.

b)

combine.

c)

decay.

d)

become parent material.

14.

You have 100 grams of radioactive C-14. The half life of C-14 is 5730 years.

How many grams are left after 2 half lives?

a)

100 grams

b)

25 grams

c)

50 grams

d)

14 grams

15.

A certain radioactive sample has a half life of 2 years. After 6 years, how much of the sample is left?

a)

1/2

b)

1/3

c)

1/16

d)

1/8

16.

If Bromine has 35 protons and a mass of 80, how many neutrons does it have?

a)

35

b)

115

c)

45

17.

How would you write the isotope name from this nuclide symbol?

a)

Sodium-23

b)

Sodium-11

c)

Sodium-12

d)

Sodium-22

18.
What do these isotopes of carbon all have in common?
a)
neutrons & mass number
b)
atomic number and neutrons
c)
atomic number and electrons
d)
protons, atomic number, and mass number
19.

Which of the following does NOT differ in isotopes of the same element?

a)

mass number

b)

number of neutrons

c)

number of protons

d)

chemical properties

20.

How many neutrons are in the following atom?

a)

47

b)

61

c)

108

d)

155

21.

How many protons are in the following atom?

a)

82

b)

125

c)

207

d)

189

22.
What is the name of the pictured isotope?
a)
Chlorine-Schmorine
b)
Chlorine-17
c)
Chlorine-35
d)
Chlorine-18
23.

What isotope is shown here? (Red = protons, gray = neutrons, blue = electrons)

a)

Beryllium-5

b)

Beryllium-9

c)

Boron-4

d)

Boron-9

24.
An atom is electrically neutral when
a)
protons and neutrons are the same
b)
protons and electrons are the same
c)
neutrons and electrons are the same
25.

_______ are atoms with the same number of protons but varying numbers of neutrons.

a)

ions

b)

elements

c)

allotropes

d)

isotopes

26.

What is the correct hyphen notation name for the isotope with 19 electrons and 21 neutrons?

a)

Potassium-40

b)

Scandium-19

c)

Potassium-21

d)

Scandium-40

27.

What is the name of the isotope with 54 protons and 79 neutrons?

a)

Xenon-79

b)

Gold-79

c)

Gold-133

d)

Xenon-133

28.

What is the Half life of this isotope?

a)

5 seconds

b)

10 seconds

c)

15 seconds

d)

20 seconds

29.

What is the Half Life of this isotope?

a)

3 days

b)

5 days

c)

8 days

d)

10 days

30.

What is the half-life of this sample?

(a)  

31.

If someone started off with a kilogram sample of this material, calculate how many grams of it would be remaining after half an hour.

Give your answer to two decimal places.

(a)  

32.
Which type of nuclear radiation is being emitted here?
a)
Alpha
b)
beta
c)
gamma 
d)
none
33.
A helium nucleus with two protons and two neutrons is called a(n) ____.  
a)
alpha particle
b)
electroscope
c)
beta particle
d)
gamma ray
34.

An isotope of silver has a half-life of 10 minutes. What fraction of the original mass would remain after one hour?

a)

1/64

b)

1/2

c)

1/4

d)

1/8

35.

An isotope of cesium (cesium-137) has a half-life of 30 years. If 1.0 mg of cesium-137 disintegrates over a period of 90 years, how many mg of cesium-137 would remain?

a)

0.5 mg

b)

0.25 mg

c)

0.125 mg

d)

0.0625 mg

36.
A 2.5 gram sample of an isotope of strontium-90 was formed in a 1960 explosion of an atomic bomb at Johnson Island in the Pacific Test Site. The half-life of strontium-90 is 28 years. In what year will only 0.625 grams of this strontium-90 remain? 
a)
1988
b)
2016
c)
2044
d)
2072
37.
What makes an element radioactive?
a)
When it's nuclei expands
b)
When it's electrons explode
c)
When it's nuclei behave
d)
When it's nuclei decay
38.

You have 100 grams of radioactive C-14. The half life of C-14 is 5730 years.

How many grams are left after 2 half lives?

a)

100 grams

b)

25 grams

c)

50 grams

d)

14 grams

39.

The time it takes for a radioactivity level to drop by a half is is the sample's ___________________.

a)

quarter life

b)

whole life

c)

wonderful life

d)

half life

40.

If the half life of a radioactive element is 100yrs, how long would it take for the radioactivity to reduce by one half?

a)

200yrs

b)

100yrs

c)

50yrs

d)

300yrs

41.
_______________ is the process by which unstable atoms emit radiation until they become stable.
a)
Radiation
b)
Chemical Reaction
c)
Radioactive Decay
d)
Isotopes
42.

The half-life of Zn-71 is 2.4 minutes. If one had 100.0 g at the beginning, how many grams would be left after 2.4 minutes has elapsed?

a)

100.0g

b)

50.0g

c)

12.5g

d)

8.5g

43.

If 10 mg of iodine 131 is given to a patient, how much is left after 8 days? The half-life of iodine-131 is 8 days.

a)

5.0mg

b)

1.25g

c)

10g

d)

10mg

44.

The half-life of Zn-71 is 2.4 minutes. If one had 100.0 g at the beginning, how many grams would be left after 7.2 minutes has elapsed?

a)

100.0g

b)

25.0g

c)

12.5g

d)

8.5g

45.
Barium-122 has a half-life of 2 minutes. A fresh sample weighing 80 g was obtained. If it takes 10 minutes to set up an experiment using barium-122, how much barium-122 will be left when the experiment begins?
a)
0.25g
b)
2.5g
c)
25g
d)
80g
46.

In a lab experiment, 2200 bacteria are placed in a petri dish. The conditions are such that the number of bacteria is able to be cut in half every 6 hours. How many bacteria would there be after 13 hours?

a)

624

b)

518

c)

490

d)

362

47.
What makes something radioactive?
a)
elements with an atomic number above 81
b)
an unstable nucleus
c)
contaminated sewage
d)
It decays over time
48.
The half-life of strontium-90 is 25 years. How much strontium-90 will remain after 100 years if the initial amount is 4.0 g?
a)
3.0g
b)
0.25mg
c)
0.3g
d)
0.25g
49.
The three types of nuclear radiation in increasing order of penetrating power are ____.  
a)
  alpha, beta, gamma 
b)
X ray, beta, gamma
c)
alpha, gamma, beta 
d)
X ray, gamma, beta 
50.

Iodine-131 has a half life of 8.07 days. What fraction of a sample of Iodine-131 is left unchanged after 16.14 days?

a)

1/2

b)

1/4

c)

1/8

d)

1/16

51.

The radioactive isotope Nickel-63 has a half life of 100 years. How much of a 10 gram sample remains after 300 years?

a)

1 gram

b)

1.25 grams

c)

0.50 grams

d)

0.075 grams

52.

The radioactive surgery used in archaeology to date organic remains is...

a)

C-12

b)

U-238

c)

C-14

d)

U-235

53.

What percentage of rubidium-87 atoms will be left after four half lives?

a)

25.0%

b)

12.5%

c)

6.25%

d)

3.125%

54.

Which radioactive element is used to determine the absolute age of late Pleistocene animal remains?

a)

rubidium-87

b)

uranium-238

c)

potassium-40

d)

carbon-14

55.

A sample of wood that originally contained 100 grams of carbon-14 now contains only 25 grams of carbon-14. Approximately how many years ago was this sample part of a living tree?

a)

2,850 years

b)

5,700 years

c)

11,400 years

d)

17,100 years

56.
If the half-life of uranium-232 is 70 years, how many half-lives will it take for 10 g of it to be reduced to 1.25 g?
a)
1 half-life
b)
2 half-lives
c)
3 half-lives
d)
4 half-lives
57.

The diagram shows 32 atoms.

16 of the Red are parent isotopes

16 of the Green are daughter isotopes

How many half-lives have occurred?

a)

0

b)

1

c)

2

d)

3

58.
Imagine you have 50,000 atoms of uranium-238. If U-238 has a half-life of 4.5 billion years, how many U-238 atoms will be left after 4.5 billion years? 
a)
25,000
b)
50,000
c)
12,500
d)
0
59.

The half-life of Zn-71 is 2.4 minutes. If 6.25 g of Zn-71 are needed for an experiment, how much should be prepared if it will take 9.6 minutes before the experiment can begin? (FIND Mi)

a)

100.0g

b)

50.0g

c)

12.5g

d)

8.5g

60.

Barium-122 has a half-life of 2 minutes. If after 10 minutes a sample of 15.0 g is left, what mass must have been initially present?

a)

30 g

b)

480 g

c)

240 g

d)

120 g

61.

The half-life of Po-218 is three minutes. If it is allowed to decay from 150.0 grams to 2.34 grams, how many half lifes have occured?

a)

6 half lifes

b)

3 half lifes

c)

8 half lifes

d)

5 half lifes

62.

The half-life of strontium-90 is 25 years. How much strontium-90 will remain after 100 years if the initial amount is 4.0 g? Round to two decimal points.

(a)  

63.
Selenium-83 has a half life of 25 minutes. How many minutes would it take for a 20 milligram sample to decay and only have 1.25 milligrams of it remaining? 
a)
25 minutes
b)
50 minutes
c)
75 minutes 
d)
100 minutes
64.

A 50.0 g sample of a radioactive element has a half-life of 40 years. How much mass will be left after 80 years?

a)

50

b)

25

c)

12.5

d)

6.25

65.
The radiation detected from a piece of rock is reduced significantly when the rock is wrapped in foil. What type of radiation is being emitted?
a)
Alpha
b)
Beta
c)
Gamma
d)
none of the above
66.
Gamma rays damage human cells/tissue.
a)
True
b)
False
67.

If we start with 64 g of radium-226, how much remains after 1 half-life?

a)
16g
b)
32g
c)

128 g

d)
4g
68.
If 10 mg of iodine 131 is given to a patient, how much is left after 24 days? The half-life of iodine-131 is 8 days.
a)
1.25mg
b)
1.25g
c)
10g
d)
10mg
69.
Selenium-83 has a half life of 25 minutes. How many minutes would it take for a 20 milligram sample to decay and only have 1.25 milligrams of it remaining? 
a)
25 minutes
b)
50 minutes
c)
75 minutes 
d)
100 minutes
70.

Geologist use the time it takes for a radioactive isotope to decay to half its original mass called a___________.

a)

radioactive decay

b)

isotope

c)

half-life

d)

carbon dating

71.
The original element that undergoes radioactive decay is known as the...
a)
daughter element
b)
half-life
c)
parent element
d)
carbon-14
72.

If we start with 64 g of radium-226, how much remains after 1 half-life?

a)
16g
b)
32g
c)

128 g

d)
4g
73.
After 4 half-lives, 1g of a sample of Krypton-85 remains unchanged.  What was the original mass of the sample?
a)
16g
b)
32g
c)
0.0625g
d)
4g
74.

If 10 mg of iodine 131 is given to a patient, how much is left after 8 days? The half-life of iodine-131 is 8 days.

a)

5.0mg

b)

1.25g

c)

10g

d)

10mg

75.

If 10 mg of iodine 131 is given to a patient, how much is left after 16 days? The half-life of iodine-131 is 8 days.

a)

5.0mg

b)

2.5mg

c)

10g

d)

10mg

76.

Name given to the atoms that are left after an atom decays.

a)

Parent

b)

Daughter

c)

Leftovers

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