HESI A2 Chemistry Practice Test

Correct Answer: B

Rationale: The correct answer is B. Temperature affects reaction rates by increasing kinetic energy. Particle size influences surface area available for collision. Concentration impacts frequency of collisions. Catalysts lower activation energy. Barometric pressure, container material, elevation, and volatility do not directly affect reaction rates. Option A includes "barometric pressure" and "facilitator," which are irrelevant. Option C includes "container material" and "elevation," which are not factors. Option D includes "volatility," which is not typically a factor in rates of reaction.

Correct Answer: B

Rationale: The correct answer is B because a balanced equation is one where the number of each type of atom is the same on both sides. This is achieved by adjusting coefficients to ensure conservation of mass. For example, in the equation 2H2 + O2 → 2H2O, there are 4 hydrogen atoms and 2 oxygen atoms on both sides. Choice A is incorrect because a balanced equation requires the number of atoms to be equal. Choice C is incorrect as a balanced equation includes both reactants and products. Choice D is incorrect because coefficients are necessary to balance the equation.

Correct Answer: C

Rationale: The correct answer is C: Boyle. Boyle's Law states that the pressure and volume of a gas are inversely proportional when temperature is constant. Boyle conducted experiments that led to this discovery. Choice A, Charles, is known for Charles's Law which relates volume and temperature. Choice B, Combine, is not a known scientist. Choice D, Gay-Lussac, is known for Gay-Lussac's Law which relates pressure and temperature.

Correct Answer: A

Rationale: The correct answer is A because at high pressure and high temperature, real gases have increased kinetic energy and are closer together, leading to decreased intermolecular forces. This results in gas molecules behaving more like ideal gases with negligible volume and no intermolecular interactions. Choice B is incorrect because at low pressure, real gases have low kinetic energy and are far apart, causing intermolecular forces to become more significant, deviating from ideal behavior. Choice C is incorrect as the boiling point of water is a specific condition related to water and does not necessarily indicate ideal gas behavior. Choice D is incorrect because under certain conditions of high pressure and high temperature, real gases can approach ideal behavior, demonstrating that real gases can exhibit ideal behavior under specific circumstances.

Correct Answer: B

Rationale: The correct answer is B: Hydrogen bonds. Hydrogen bonds are formed between a hydrogen atom in a polar covalent bond and a highly electronegative atom like oxygen or nitrogen. In water, hydrogen bonds contribute to its high boiling point, surface tension, and density anomalies. In DNA, hydrogen bonds between base pairs help maintain the double helix structure. Incorrect choices: A: Oxygen links - This is not a recognized term in chemistry and does not accurately describe the type of bonds discussed. C: Dipolar bonds - While dipole-dipole interactions are involved in hydrogen bonding, the term "dipolar bonds" is not commonly used to refer to this specific type of bond. D: N/A - This choice does not provide any information related to the question and is not a valid option.