Chapter 21, Problem 9PS

Interpretation Introduction

Interpretation: To interpret if calcium is found in free state or not in earth’s crust.

Concept introduction: Earth’s crust is the outermost solid shell of planet earth. Almost $99$ percent of earth’s crust is made up of just $10$ elements. These $10$ elements are oxygen, silicon, aluminum, iron, calcium, sodium, magnesium, potassium, titanium, and hydrogen.

Calcium is fifth most abundant element in earth’s crust. It makes up of $4.2$ percent of earth’s crust by weight.

Most of the elements in earth’s crust are found in the form of rocks and minerals.