A Radioactive Source Has a Half-Life of 2 Min

question 4

Multiple Choice

A radioactive source has a half-life of 2 min. At time t = 0 it is placed near a detector and the counting rate is observed to be 3000 counts/s. If the detection efficiency is 25%, how many radioactive nuclei are there at time t = 0?

• A) 1.04 × 10⁶.
• B) 1.67 × 10⁶
• C) 2.08 × 10⁶
• D) 3.41 × 10⁶
• E) 3.79 × 10⁶

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Definitions:

REM Sleep

A phase of sleep involving rapid eye movements, where dreaming and increased brain activity occur.

Parasomnia

A category of sleep disorders that involve abnormal and unnatural movements, behaviors, emotions, perceptions, and dreams.

REM Sleep

A phase of sleep characterized by rapid eye movements and is the period where most dreams occur.

Sleep Architecture

The structure of different stages of sleep as they cycle through the night, typically involving variations in REM and non-REM sleep phases.