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Unit 6 Review

Total questions: 16

Worksheet time: 15mins

Name
Class
Date
1.

Which law states that younger rocks lie above older rocks if the layers have not been disturbed?

a)

superposition

b)

cross-cutting

c)

unconformity

d)

uniformitarianism

2.

Explain the difference between Relative Dating and Absolute Dating.

4 lines
3.
The length of time required for half of the radioactive atoms in a sample to decay is its...
a)
era
b)
age
c)
half-life
d)
eon
4.

The original element that undergoes radioactive decay is known as the _______.

a)

daughter element

b)

half-life

c)

parent element

d)

carbon-14

5.
When an unstable radioactive atom decays, it usually turns into:
a)
a more stable atom
b)
a less stable atom
c)
the exact same atom but with less pure energy
d)
empty space
6.

Examine this table of different Radioactive elements and the number of years half of their atoms decay.


How many years would pass if only 12.5% of the Carbon-14 radioactive elements are left?

4 lines
7.

The percent of the parent isotope remaining after 4 Half-Lives is ____.

a)

50%

b)

25%

c)

12.5%

d)

6.25%

8.

What is the correct order of the rock layers from oldest to youngest?

a)

B, C, D, E, A

b)

E, D, C, B, A

c)

A, B, C, D, E

d)

B, C, D, A, E

9.

What is the correct order of the rock layers from oldest to youngest?

a)

F, E, C, B, A, D

b)

F, E, D, C, B, A

c)

A, B, C, D, E, F

d)

D, F, E, C, B, A

10.

What law states that any geologic feature that cuts across other layers is younger than layers it cuts across?

a)

Law of superpostion

b)

Law of layers

c)

Law of inclusion

d)

Law of crosscutting

11.

Unstable atoms that decay (change) are considered radioactive _________.

a)

Isotopes

b)

Half-Life

c)

Absolute Dating

d)

Radiometric Dating

12.
Why are isotopes with short half-lives not useful for dating very old rocks?
a)
because not enough of the parent isotope remains to measure accurately
b)
because not enough of the daughter product has formed to be detectable
c)
because neither the parent isotope nor the daughter product will be detectable
d)
because very old rocks would never have contained these isotopes
13.

When did a mass extinction of dinosaurs and many land plants occur? (NOTE: use pages 8 & 9 of your ESRT)

a)

65.5 mya

b)

251 mya

c)

300 mya

d)

440 mya

14.
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
15.

You find a rock sample with radioactive atoms present. If 12.5% of the original radioactive atoms were present, how many half-lives has the rock been around for?

a)

zero

b)

1

c)

2

d)

3

16.

An archeologist found an ancient skeleton estimated to be 10,000 to 25,000 years old. Which radioactive isotope would be the most useful for finding the age of the skeleton?

a)

Carbon-14

b)

Potassium-40

c)

Uranium-238

d)

Rubidium-87