Rubidium-87 Decays by Beta Decay with a Half-Life of 4

question 54

Multiple Choice

Rubidium-87 decays by beta decay with a half-life of 4.9 × 10¹⁰ yr.How many ⁸⁷Rb atoms are in a moon rock sample that has a rubidium decay rate of 3,500 disintegrations per hour?

• A)9.0 × 10¹⁶ atoms
• B)4.3 × 10^-4 atoms
• C)2.2 × 10¹⁸ atoms
• D)2.5 × 10¹⁴ atoms
• E)1.7 × 10¹⁴ atoms

---

Definitions:

Plateau

A state of little or no change following a period of activity or progress.

Hormonal Control

The regulation of bodily functions through the secretion of hormones by the endocrine glands, impacting processes like metabolism, growth, and reproduction.

Estrus Cycle

The reproductive cycle in female mammals, marked by periods of sexual receptivity (estrus) and potential for becoming pregnant.

Pituitary Gland

A small, pea-sized gland located at the base of the brain, crucial for regulating vital body functions and general wellbeing through the secretion of hormones.