The Rb-87/Sr-87 Method of Dating Rocks Is Often Used by Geologists

question 71

Multiple Choice

The Rb-87/Sr-87 method of dating rocks is often used by geologists: t_1/2 = 6.0 × 10¹⁰ yr Estimate the age of a rock sample in which the present-day mole ratio of Rb-87 to Sr-87 is 36:1.

• A)2.4 × 10⁹ yr
• B)1.7 × 10⁹ yr
• C)3.1 × 10¹¹ yr
• D)4.1 × 10^-11 yr
• E)3.6 × 10¹¹ yr

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Definitions:

Nuclear Envelope

The double membrane structure that surrounds the nucleus in eukaryotic cells, separating the contents of the nucleus from the cytoplasm.

Telophase

The final phase of cell division, during which chromosomes de-condense, nuclear envelopes re-form around the daughter nuclei, and cytokinesis usually occurs, resulting in two separate cells.

Anaphase

Stage of mitosis during which sister chromatids separate and move toward opposite spindle poles.

Opposite Poles

Refers to the two extremities of an axis, having completely contrasting characteristics, typically used in the context of magnets or geographical poles.