Elevated Levels of Iridium Are Found in the Geologic Layer

question 20

Multiple Choice

Elevated levels of iridium are found in the geologic layer at the K-T boundary.Is this unusual?

• A)Yes. Iridium is a common metal on Earth but rarely accumulates in a singe layer.
• B)No. Iridium is a rare element on Earth, but geological layers of iridium are not uncommon.
• C)Yes. Iridium is a rare metal on Earth.
• D)Yes. Composition differences between geological layers tend to equilibrate over time.

---

Definitions:

Thermal Conditions

Refers to the temperature and heat-related circumstances affecting or controlling a process or reaction.

Symmetry-Allowed

In quantum chemistry, a process or transition is symmetry-allowed if it does not violate symmetry rules governing molecular transformations.

Reaction Outcome

The final products, yields, and implications of a chemical reaction based on the reactants and conditions employed.

Major Organic Product

The primary substance produced with the highest yield in a reaction involving organic compounds.