HESI A2 Chemistry Questions

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.

Correct Answer: A

Rationale: Acids have a sour taste due to their ability to release hydrogen ions (H+) in solution. This sour taste is a key characteristic property of acids. Bitter taste (Choice B) is associated with bases, not acids. Reacting with bases (Choice C) is a general property of acids, not a characteristic property. Slippery feel (Choice D) is an attribute of bases, not acids. Thus, the correct answer is A because of the unique sour taste exhibited by acids.

Correct Answer: D

Rationale: The correct answer is D: Baking soda. Baking soda, or sodium bicarbonate, has a pH value greater than 7, typically around 8.4 when dissolved in water. This is because it is a basic compound that releases hydroxide ions when dissolved in water, resulting in a pH above 7. In contrast, choices A, B, and C have pH values below 7. Water (choice A) is neutral with a pH of 7, vinegar (choice B) is acidic with a pH below 7, and lemon juice (choice C) is also acidic due to the presence of citric acid. Therefore, baking soda is the only substance among the choices that has a pH value greater than 7.

Correct Answer: D

Rationale: The correct answer is D: High specific heat. Water's ability to form hydrogen bonds allows it to absorb and retain a significant amount of heat before its temperature changes. This property is essential for regulating temperature in living organisms and maintaining stable environments. A: Lack of cohesiveness - This is incorrect because water's hydrogen bonding actually promotes cohesion, leading to high surface tension. B: Low surface tension - This is incorrect because water's hydrogen bonding contributes to high surface tension. C: Use as a nonpolar solvent - This is incorrect because water is a polar solvent, not nonpolar, due to its hydrogen bonding capabilities.

Correct Answer: D

Rationale: The correct answer is D: Glucose. Glucose is a product of photosynthesis, as plants use sunlight, water, and carbon dioxide to produce glucose (sugar) and oxygen. Glucose is a type of carbohydrate that serves as a primary source of energy for plants and other organisms. Carbon dioxide (A) is one of the reactants needed for photosynthesis, not a product. Oxygen (B) is released as a byproduct of photosynthesis, not a product. Water (C) is also a reactant in photosynthesis, not a product. Therefore, the correct answer is D because glucose is the main product of photosynthesis.