Chemistry HESI A2 Practice Test

Correct Answer: D

Rationale: The correct answer is D: Crystalline shape. Ionic compounds have a regular, repeating arrangement of ions in a crystal lattice structure due to strong electrostatic forces between oppositely charged ions. This leads to the formation of distinct geometric shapes, known as crystalline shapes. Choice A is incorrect because ionic compounds typically have high melting points due to strong ionic bonds. Choice B is incorrect as ionic compounds are good conductors when dissolved in water or in a molten state. Choice C is incorrect because ionic compounds involve transfer, not sharing, of electrons between ions.

Correct Answer: D

Rationale: To determine how many times more acidic a substance is based on pH, we use the formula: times more acidic = 10^(pH difference). In this case, the pH difference is 3 - 5 = -2. So, times more acidic = 10^(-2) = 1/1000. Therefore, a substance with a pH of 3 is 1,000 times more acidic than a substance with a pH of 5. Choice A (8) is incorrect because it does not reflect the pH difference between 3 and 5. Choice B (2) is incorrect as it does not consider the logarithmic scale of pH. Choice C (100) is incorrect as it does not accurately calculate the pH difference and the corresponding acidity factor.

Correct Answer: B

Rationale: Failed to generate a rationale after 5 retries.

Correct Answer: A

Rationale: Failed to generate a rationale after 5 retries.

Correct Answer: C

Rationale: The given chemical equation shows aluminum replacing hydrogen in sulfuric acid, which is a single replacement reaction. In this type of reaction, one element displaces another in a compound. Here, Al replaces H in H2SO4 to form Al2(SO4)3 and HNO3. The other choices are incorrect because a decomposition reaction involves a single compound breaking down into simpler substances, a synthesis reaction involves two or more substances combining to form a new compound, and a double replacement reaction involves the exchange of ions between two compounds.