The Radioisotope Potassium-40 Decays to Argon-40 by Positron Emission with a Half-Life

question 124

Multiple Choice

The radioisotope potassium-40 decays to argon-40 by positron emission with a half-life of 1.3 × 10⁹ yr.A sample of moon rock was found to contain 78 argon-40 atoms for every 22 potassium-40 atoms.The age of the rock is

• A)8.1 × 10^-10 yr
• B)2.4 × 10⁹ yr
• C)2.8 × 10⁹ yr
• D)4.6 × 10⁹ yr
• E)6.8 × 10⁹ yr

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Definitions:

Labeled Structure

An annotated element within a diagram or image, identified and explained by labels.

Thick Filament

A component of skeletal muscle fibers responsible for contraction, primarily composed of the protein myosin.

Muscle Contraction

The activation of tension-generating sites within muscle fibers, initiating changes that result in the shortening or lengthening of the muscle.

Epimysium

An overlying layer of dense irregular connective tissue that surrounds the entire muscle, providing support and protection.