The graph shows the decay of two different radioactive nuclei, Source A and Source B.
How long does it take Source B to complete two half-lives?
a- 10 s
b- 5 s
c- 40 s
d- 20 s
d- 20 s
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I apologize for my mistake in the previous response. However, I cannot provide the answer without the graph or information about the half-life of Source B. Please provide more information so I can assist you accurately.
Use the graph to answer the question.
The graph shows the decay of two different radioactive nuclei, Source A and Source B.
The vertical axis is labeled number of undecayed nuclei and ranges from 0 to 120 in increments of 20. The horizontal axis is labeled time (s) and ranges from 0 to 40 in increments of 5. The graph of source A is a dashed concave up curve that slopes downward from 105 on the vertical axis and overlaps the horizontal axis from 35 to 40. The graph of source B is a concave up curve that slopes downward from 120 on the vertical axis. The line falls down to 36 for time = 40 seconds. The values used in the description are approximate.
How long does it take Source B to complete two half-lives?
(1 point)
Responses
10 s
10 s
5 s
5 s
20 s
20 s
40 s
Assuming that the half-life of Source B is not given but can be estimated from the graph, we can observe that the number of undecayed nuclei of Source B decreases by half from 120 to 60 at approximately 10 seconds. This is the first half-life. The second half-life occurs when the number of undecayed nuclei decreases by half again from 60 to 30. This happens at around 20 seconds. Therefore, the answer is 20 seconds.
The correct response is:
- d) 20 s
To determine how long it takes for Source B to complete two half-lives, we need to understand what a half-life is. The half-life of a radioactive substance is the time it takes for half of the nuclei in a sample to decay.
Looking at the graph, we can see that Source B takes 20 seconds to complete one half-life. This means that after 20 seconds, half of the nuclei in Source B would have decayed.
To find the time it takes for Source B to complete two half-lives, we multiply the half-life by 2, since two half-lives need to occur for the complete decay of the sample.
Therefore, the time it takes for Source B to complete two half-lives is 20 seconds x 2 = 40 seconds.
Therefore, the correct answer is c- 40 s.