An Echo-Free Structure Is Described As

question 16

Multiple Choice

An echo-free structure is described as:

• A) echogenic.
• B) sonolucent.
• C) heterogeneous.
• D) homogeneous.

---

Definitions:

Earth's Atmosphere

The layer of gases surrounding Earth, retained by the planet's gravity, composed primarily of nitrogen and oxygen, and protecting life by absorbing ultraviolet solar radiation and reducing temperature extremes.

Ancient Society

Human societies that existed in a time period that could be considered ancient or prehistoric, often characterized by early developments in social organization, culture, and technology.

Continuous Matter

A classical concept describing matter as an infinitely divisible entity, unlike the quantum concept which describes matter in terms of discrete particles.

Observable Properties

Characteristics of a substance that can be determined through direct observation or with the help of simple tests without changing the substance's identity.