The Half-Life of Cobalt-60 Is $5.3$ Years, While That of Strontium-90 Is About 29 Years

question 21

Multiple Choice

The half-life of cobalt-60 is $5.3$ years, while that of strontium-90 is about 29 years. Suppose you have samples of both isotopes, and that they initially contain equal numbers of atoms of these isotopes. How will the activities (number of decays per second) of the samples compare?

• A) The activities will be equal.
• B) The activities cannot be compared without more information.
• C) The activity of the strontium- 90 sample will be greater.
• D) The activity of the cobalt-60 sample will be greater.

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Definitions:

Working Through

A psychoanalytic process involving the repeated examination and exploration of problems, emotions, and past experiences to achieve insight and resolve internal conflicts.

Interpretation

In therapy, the act of a therapist explaining or providing insight into aspects of a client's thoughts, behaviors, or dreams to uncover underlying meanings.

Displacement

In psychology, a defense mechanism where an individual shifts emotional reactions from a real source of distress to a safer or more acceptable substitute.

Intense Reaction

A highly amplified emotional or physical response to a specific trigger or situation.