Iodine-131, T_1/2 = 8

question 12

Multiple Choice

Iodine-131, t_1/2 = 8.0 days, is used in the diagnosis and treatment of thyroid gland diseases. If a laboratory sample of iodine-131 initially emits 9.95 × 10¹⁸ β particles per day, how long will it take for the activity to drop to 6.22 × 10¹⁷ β particles per day?

• A) 2.0 days
• B) 16 days
• C) 32 days
• D) 128 days
• E) None of the answers is correct.

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Definitions:

Insight Learning

A type of learning characterized by a sudden realization of a problem's solution.

Conditioned Response (CR)

The learned response to the conditioned stimulus that occurs after a conditioned stimulus–unconditioned stimulus pairing.

Conditioned Stimulus (CS)

A previously neutral stimulus that, after being associated with an unconditioned stimulus, elicits a conditioned response.

Unconditioned Response (UR)

An unlearned reaction that is automatically elicited by the unconditioned stimulus.