The Decay Rate of an Alpha Emitter Sample Is 975

question 54

Multiple Choice

The decay rate of an alpha emitter sample is 975 disintegrations/minute. Exactly 1 hour later the sample decays at a rate of 644 disintegrations/minute. What is the half-life of this alpha emitter?

• A) 100 min
• B) 27.5 min
• C) 2.79×10 ^{- 2} min
• D) 6.91×10 ^{- 3} min
• E) none of these

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Definitions:

Unrealized Gain

The potential profit that exists on paper resulting from an investment that has not yet been sold for cash.

Fair Value Adjustment

A process of adjusting the book value of an asset or liability to reflect its current market value.

Available-for-Sale

A category of securities that are not classified as held-to-maturity or trading securities, and are recorded at fair value.

Unrealized Loss

A loss that occurs on paper due to a decrease in the value of an investment, but has not been realized through a transaction.