HESI A2 Chemistry Practice Questions - Nurselytic

Correct Answer: B

Rationale: In a single displacement reaction, an active element displaces a less active element in a compound. This process involves one element replacing another in a compound, resulting in the formation of a new compound. Option A is incorrect because a single displacement reaction does not involve the decomposition of a compound into two substances. Option C is incorrect because it describes a precipitation reaction, not a single displacement reaction. Option D is incorrect because it describes oxidation-reduction reactions, not specifically single displacement reactions.

Correct Answer: C

Rationale: A saturated solution contains the maximum concentration of solute that can be dissolved in a specific amount of solvent at a particular temperature. Once a solution is saturated, adding more solute will not increase its concentration since the excess solute will not dissolve and will instead form a precipitate, indicating that the solution is at its maximum capacity.

Choices A, B, and D are incorrect because a saturated solution has reached its limit in dissolving solute, so it cannot contain more solute than it can dissolve (choice
A), less solute than it can dissolve (choice
B), or a precipitate that lowers the concentration of the solute in the solvent (choice
D).

Correct Answer: D

Rationale: Silicon has an atomic mass greater than that of sodium. The atomic mass of silicon is approximately 28.0855 u, whereas the atomic mass of sodium is approximately 22.9898 u.
Therefore, silicon has a greater atomic mass compared to sodium. Boron, Oxygen, and Fluorine have atomic masses lower than sodium, making them incorrect choices in this context.

Correct Answer: C

Rationale: Arsenic and silicon are both examples of metalloids. Metalloids have properties that lie between those of metals and nonmetals. They exhibit characteristics of both groups, making them versatile elements with various applications in different industries.
Choice A (metals) is incorrect as arsenic and silicon do not exhibit typical metallic properties.
Choice B (nonmetals) is incorrect as they do not possess all the properties of nonmetals.
Choice D (heavy metals) is incorrect as heavy metals refer to a different group of elements with high atomic weights, and arsenic and silicon are not categorized as heavy metals.

Correct Answer: A

Rationale: The correct answer is A: 0. Ionic compounds have a net charge of 0 because they are formed by the combination of positively charged ions (cations) and negatively charged ions (anions) in a way that neutralizes their charges. This balanced combination results in an electrically neutral compound.
Therefore, the net charge of an ionic compound is typically 0.

Choices B, C, and D are incorrect because ionic compounds are designed to have a total neutral charge, with the positive charges balancing out the negative charges.