HESI A2 Chemistry Questions

Correct Answer: A

Rationale: The correct answer is A: Uranium. Uranium has the highest atomic number among the options provided. Atomic number represents the number of protons in the nucleus of an atom. Uranium has an atomic number of 92, which is higher than the other elements listed. Hydrogen has an atomic number of 1, Radon has an atomic number of 86, and Bismuth has an atomic number of 83. Therefore, Uranium has the highest atomic number, making it the correct choice.

Correct Answer: A

Rationale: The correct answer is A: Covalent bond. In a covalent bond, two atoms share electrons to complete their outer electron shells and achieve stability. This sharing results in a strong bond between the atoms. Ionic bonds involve the transfer of electrons, metallic bonds involve a "sea" of shared electrons in a metal lattice, and hydrogen bonds are weaker interactions between a hydrogen atom and an electronegative atom. Covalent bonds are the only option where electrons are shared between atoms to form a stable bond.

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: A

Rationale: The correct answer is A: boron. Diatomic molecules consist of two atoms of the same element bonded together. Boron exists as a monatomic element, meaning it exists as single atoms. Fluorine, oxygen, and nitrogen exist naturally as diatomic molecules (F2, O2, N2) due to their stability when bonded together. Boron does not form diatomic molecules because it is less stable in that form.

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.