HESI A2 Chemistry Practice Test

Correct Answer: B

Rationale: The typical oxidation state of oxygen in most compounds is -2. Oxygen is highly electronegative and tends to gain 2 electrons to achieve a stable octet configuration. This results in an oxidation state of -2 in compounds like water (H2O) and carbon dioxide (CO2). Therefore, choice B is correct. Choice A (-1) is incorrect because oxygen rarely has an oxidation state of -1 in compounds. Choice C (0) is incorrect as oxygen doesn't usually have an oxidation state of 0; it prefers to gain electrons. Choice D (-3) is incorrect as it is an uncommon oxidation state for oxygen in compounds.

Correct Answer: A

Rationale: The correct answer is A: Covalent bonds. Covalent bonds involve a complete sharing of electrons between atoms with partially filled outer shells. This sharing allows atoms to achieve stable electron configurations. Hydrogen bonds involve an electrostatic attraction between a hydrogen atom and a highly electronegative atom. Proportional bonds are not a recognized type of chemical bond. Choice D, N/A, is not a valid option for this question.

Correct Answer: C

Rationale: The correct answer is C: Chemical bonds. Chemical bonds encompass both ionic and covalent bonds, making them an intermediate between the extremes represented by these two types of bonds. Ionic bonds involve complete transfer of electrons, while covalent bonds involve sharing of electrons. Therefore, chemical bonds, which encompass both types, are the most appropriate choice. Summary: A: Ionic bonds - involve complete transfer of electrons, not an intermediate between extremes. B: Covalent bonds - involve sharing of electrons, not an intermediate between extremes. D: Polar bonds - a specific type of covalent bond, not representing the intermediate nature of chemical bonds.

Correct Answer: A

Rationale: The correct answer is A: Order of increasing atomic number. This is because the periodic table is arranged based on the number of protons in the nucleus of an atom, which is the atomic number. This arrangement helps in organizing elements based on their properties and allows us to predict the behavior of elements. Choice B (Alphabetical order) is incorrect because elements are not arranged alphabetically but based on their atomic number. Choice C (Order of increasing metallic properties) is incorrect because while elements are grouped based on similar properties, the overall arrangement is not solely based on metallic properties. Choice D (Order of increasing neutron content) is incorrect as the periodic table is based on atomic number (number of protons), not neutron content.

Correct Answer: C

Rationale: The statement that the volume of a gas is directly proportional to its absolute temperature at constant pressure aligns with Charles' Law. This law states that for a fixed amount of gas at a constant pressure, the volume of the gas is directly proportional to its absolute temperature. As the temperature increases, the volume of the gas also increases proportionally. This relationship is depicted by the equation V1/T1 = V2/T2. The other choices are incorrect because the Combined Gas Law involves pressure, volume, and temperature changes simultaneously; Boyle's Law describes the inverse relationship between pressure and volume at constant temperature, and the Ideal Gas Law is a combination of Boyle's, Charles', and Avogadro's Laws.