Question

The graph below shows the half life values of parent isotopes.

The bar graph shows 'Parent Isotope' labeled on the x axis and 'Half-life (in billion years)' labeled on the y axis. The first bar is labeled Uranium-238 and its height is 4. The second bar is labeled 'Thorium-235' and its height is 14, the third bar is labeled 'Potassium-40' and its height is 1.5', and the fourth bar is labeled 'Rubidium-87' and its height is 49.

Based on the graph, it can be concluded that the isotope which is most likely to be found with 6.25% of its original amount in 16 billion years?

Rubidium-87
Uranium-238
Potassium-40
Thorium-235

Answer 1

Ok, I'm not gonna try to plug a formula for this one. Putting this simply, every substance starts at 100% of it's value. After a half life, it will be 50%. Another half life, it will be 25%. How many half lifes will it take to get to 6.25%?

Answer 2

5

Answer 3

100/2 = 50

50/2 = 25

25/2 = 12.5

12.5/2 = 6.25

Answer 4

so 4

Answer 5

yes

Answer 6

so what next?

Answer 7

so now that we know how many half lives it takes to get to 6.25%, let's divide the given time, 16 billion years, by 4

Answer 8

and that will get you the half life of the right element

Answer 9

c?

Answer 10

potassium has a half life of 1.5 billion, it would go through over 10 half lives by then

Answer 11

d?

Answer 12

what is 16 divided by 4?

Answer 13

4

Answer 14

which element has a half life of 4 billion years?

Answer 15

i mean itd have to be one of the two left but idk bc im confused

Answer 16

again

Answer 17

let's start from the beginning

Answer 18

how many half lives does it take to get to 6.25% of the original size?

Answer 19

4

Answer 20

so then in 16 billion years, the element we're looking for would have to go through 4 half lives

Answer 21

which means in one half life, it would be 16 billion years divided by 4

Answer 22

you said 16 billion divided by 4 is 4 billion years. which bar is at the value of 4 billion years?

Answer 23

b

Answer 24

that's correct

Answer 25

lol only took me 3 tries lol

Answer 26

All scientific theories on the solar system are based on

biased scientific data
non-testable facts
non-observable information
study of current evidences

Answer 27

i think this one is d?

Answer 28

yes

Answer 29

ok cool

Answer 30

finally on q30

Answer 31

Scientists have discovered a solar system at a distance of 2000 AU from Earth. What is the distance, in kilometers, between the new solar system and Earth?

300 million kilometers
300 billion kilometers
20 million kilometers
20 billion kilometers

Answer 32

b?

Answer 33

every AU is 149,597,870.7 km

Answer 34

oh wait

Answer 35

sorry I didn't see you already had an answer

Answer 36

yes that's correct

Answer 37

which of these statements best compares P waves and S waves of an earthquake?

Both S waves and P waves travel through oxygen gas.
Both S waves and P waves travel through carbon dioxide gas.
S waves do not tavel through molten rocks but P waves travel through molten rocks.
P waves do not tavel through molten rocks but S waves travel through molten rocks.

Answer 38

i think c

Answer 39

A and B are comparisons, C and D are contrasts

Answer 40

but I'm starting to think whoever wrote the question didn't care about that

Answer 41

yeah

Answer 42

yeah C is right

Answer 43

okay cool

Answer 44

im gonna start a new question