ASVAB General Science Practice Test 743540

Questions 5
Topics Compound, Exoskeleton, Groups, Infiltration, Troposphere

Study Guide

Compound

A compound is a substance containing two or more different chemical elements bound together by a chemical bond. In covalent compounds, electrons are shared between atoms. In ionic compounds, one atom borrows an electron from another atom resulting in two ions (electrically charged atoms) of opposite polarities that then become bonded electrostatically.

Exoskeleton

An exoskeleton (external skeleton) is common in arthropods like insects, spiders, and crustaceans.

Groups

The columns of the Periodic Table are called groups and all elements in a group have the same number of electrons in their outer electron shell. The group that an element occupies generally determines its chemical properties as the number of outer shell electrons establishes the way it reacts with other elements to form molecules. So, because each element has the same number of electrons in its outer shell, each has similar reactivity.

Infiltration

The water then accumulates as runoff and eventually returns to bodies of water or is absorbed into the Earth (infiltration) and becomes part of the water table, an underground resevoir of fresh water.

Troposphere

The Earth's atmosphere has several layers starting with the troposphere which is closest in proximity to the surface. Containing most of the Earth's breathable air (oxygen and nitrogen), it's a region with warmer temperatures closer to the surface and cooler temperatures farther away which results in the rising and falling air that generates weather.