The Half-Life of Cobalt-60 Is 5

question 83

Multiple Choice

The half-life of cobalt-60 is 5.3 years,while that of strontium-90 is 28 years.Suppose that samples of cobalt-60 and strontium-90 are such that they initially have the same activity (number of decays per second) .What is true about the initial numbers of cobalt-60 and strontium-90 nuclei in these samples?

• A) There are more strontium-90 than cobalt-60 nuclei.
• B) There are equal numbers of cobalt-60 and strontium-90 nuclei.
• C) There are more cobalt-60 than strontium-90 nuclei.
• D) It is not possible to compare numbers of nuclei without knowing the masses of the samples.

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Definitions:

Audience Effect

The influence that the presence of others has on an individual's performance or behavior.

Drive Theory

A psychological framework suggesting that motivation arises from biological needs that drive behavior to satisfy them.

Social Facilitation

The tendency for people to perform differently when in the presence of others than when alone, typically showing improved performance on simple or well-rehearsed tasks.

Social Presence

The degree to which a person feels that another person, through mediated communication, appears to be physically present.