Hard Water in Parts of the Midwest May Have a Calcium

question 21

Multiple Choice

Hard water in parts of the Midwest may have a calcium ion concentration as high as 400 ppm.What is this calcium ion concentration when expressed as a percentage?

• A)40 percent
• B)4 percent
• C)0.4 percent
• D)0.04 percent

---

Definitions:

Physiological Needs

Basic human necessities required for survival, such as food, water, shelter, and sleep; the foundational level in Maslow's hierarchy of needs.

Affiliation Needs

The inherent human desire to belong to a group or form close and interpersonal relationships.

Esteem Needs

Refers to the human desire for respect, self-esteem, and recognition from others, considered a higher-level need in Maslow's hierarchy of needs.

Security Needs

The requirements essential for an individual's or organization's safety, protection, and freedom from threats or harm.