WGU D425 SCIE 2030 Introduction to Chemistry OA READINESS EXAM GUIDE Q & S 2025/2026

1. Which of the following is the most abundant element in the
human body?
 a) Carbon
 b) Oxygen
 c) Hydrogen
 d) Nitrogen
 Answer: b) Oxygen
 Rationale: Oxygen is the most abundant element, making up
about 65% of the human body by weight.
2. What type of bond is primarily responsible for the secondary
structure of proteins?
 a) Ionic bonds
 b) Hydrogen bonds
 c) Covalent bonds
 d) Van der Waals forces
 Answer: b) Hydrogen bonds
 Rationale: Hydrogen bonds stabilize the secondary structure,
particularly the alpha helices and beta sheets in proteins.
3. In an exergonic chemical reaction, the products have...
 a) More energy than the reactants
 b) Less energy than the reactants
 c) The same amount of energy as the reactants
 d) It depends on the reaction type
 Answer: b) Less energy than the reactants
 Rationale: Exergonic reactions release energy, meaning the
products have lower energy than the reactants.
4. Which of the following elements is most likely to form a
cation?