HESI A2 Chemistry Questions

Correct Answer: A

Rationale: The correct answer is A: 7. In a neutral solution, the concentration of H+ ions equals the concentration of OH- ions, resulting in a pH of 7. This signifies a balance between acidity and alkalinity. Choice B (0) is incorrect as it represents a strong acid, choice C (14) is incorrect as it represents a strong base, and choice D (4) is incorrect as it indicates an acidic solution.

Correct Answer: B

Rationale: The correct answer is B: Halogens. Halogens are a group of elements in Group 17 of the periodic table, including chlorine, fluorine, and iodine. They are known for their high reactivity and tendency to form salts with metals. Alkali metals (A) are in Group 1, transition metals (C) are in the middle part of the periodic table, and noble gases (D) are in Group 18. These choices are incorrect as they do not include chlorine, fluorine, and iodine, which are characteristic of the halogens.

Correct Answer: B

Rationale: The correct answer is B: Na. Sodium's chemical symbol is Na because it is derived from its Latin name "natrium." N represents nitrogen, Cl represents chlorine, and H represents hydrogen, making them incorrect choices. Remember to consider the element's name origins for accurate symbol identification.

Correct Answer: C

Rationale: The correct answer is C: Evaporation. During evaporation, a liquid changes into a gas at the surface level due to the absorption of heat energy. This process occurs at temperatures below the boiling point of the liquid. Condensation (Choice A) is the opposite process, where a gas turns into a liquid. Sublimation (Choice B) is the phase change from solid directly to gas without passing through the liquid phase. Melting (Choice D) is the phase change from solid to liquid. Therefore, the correct choice for the phase change from liquid to gas is evaporation.

Correct Answer: A

Rationale: The correct answer is A: Neutralization reaction. In this reaction, an acid and a base combine to form water and a salt. This process involves the transfer of protons from the acid to the base, resulting in the formation of water and a salt. Neutralization reactions are characterized by the formation of a neutral product (water) from the acidic and basic reactants. Option B: Decomposition reaction involves a compound breaking down into simpler substances. Option C: Combustion reaction involves a substance reacting with oxygen to produce heat and light. Option D: Redox reaction involves the transfer of electrons between reactants. These options do not accurately describe the reaction between an acid and a base to form water and salt.