In an Unweathered Sample of Igneous Rock,the Ratio of an Unstable

question 40

Multiple Choice

In an unweathered sample of igneous rock,the ratio of an unstable isotope to its stable daughter isotope is 1/15.If no daughters were present at the time the rock cooled below closure temperature,and the half-life of the reaction is 50 million years,how old is the rock?

• A)200 million years
• B)400 million years
• C)750 million years
• D)None of the above are correct.

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Definitions:

Anterograde Amnesia

An inability to recall events that occur after some disturbance to the brain.

Declarative Amnesia

The loss of capability to recall explicit information, including facts and personal events, usually due to brain injury or disease.

Semantic Memory

A type of long-term memory involving the ability to remember meanings, concept-based knowledge, and factual information.

Episodic Memory

A type of long-term memory that involves recollecting specific events, situations, and experiences.