HESI A2
Chemistry HESI A2 Practice Test
1. What is an alloy in which another metal is dissolved in mercury (Hg) called?
- A. Electrum
- B. Amalgam
- C. Solder
- D. Bronze
Correct answer: B
Rationale: An amalgam is a type of alloy where another metal is dissolved in mercury (Hg). This process forms a unique mixture that has various applications in dentistry, chemistry, and other fields. Electrum is a natural alloy of gold and silver, solder is a metal alloy used to join other metals together, and bronze is a copper-tin alloy. Therefore, the correct answer is B - Amalgam.
2. What is the term used when an atom gains one or more electrons?
- A. Cation
- B. Anion
- C. Isotope
- D. Electron
Correct answer: B
Rationale: When an atom gains electrons, it becomes negatively charged and is called an anion. An anion is formed when an atom gains one or more electrons, leading to an excess of negative charge. Choice A, 'Cation,' is incorrect because a cation is formed when an atom loses electrons, resulting in a positively charged ion. Choice C, 'Isotope,' refers to atoms of the same element with different numbers of neutrons and is not related to gaining electrons. Choice D, 'Electron,' is the particle that an atom gains to become an anion, not the term for the atom itself after gaining electrons.
3. What is the name of the process by which a gas turns into a liquid?
- A. Sublimation
- B. Condensation
- C. Evaporation
- D. Deposition
Correct answer: B
Rationale: The correct answer is B: Condensation. Condensation is the process where gas transforms into a liquid. When gas cools down, it loses energy and its particles come closer, leading to the formation of liquid droplets. Sublimation is the direct transition from solid to gas without passing through the liquid state. Evaporation is the process of liquid turning into a gas, and deposition is the transition of gas directly into a solid. Therefore, choices A, C, and D are incorrect as they describe different phase transitions.
4. How much concentrated HCl should be used to prepare 500 mL of a 0.100 M HCl solution?
- A. 75 mL
- B. 100 mL
- C. 125 mL
- D. 150 mL
Correct answer: B
Rationale: To prepare a 0.100 M HCl solution with a volume of 500 mL, you can use the formula C1V1 = C2V2, where C1 is the concentration of the concentrated HCl solution, V1 is the volume of concentrated HCl solution used, C2 is the desired concentration (0.100 M), and V2 is the final volume (500 mL). Rearranging the formula to solve for V1, you get V1 = (C2V2) / C1. Plugging in the values (0.100 M)(500 mL) / C1 = 100 mL, which means 100 mL of concentrated HCl should be used to prepare 500 mL of a 0.100 M HCl solution. Therefore, the correct answer is 100 mL. Choice A (75 mL), Choice C (125 mL), and Choice D (150 mL) are incorrect as they do not match the calculated volume needed to prepare the desired concentration of HCl solution.
5. Which particles are emitted during radioactivity?
- A. Electrons
- B. Protons
- C. Radiation
- D. Neutrons
Correct answer: C
Rationale: During radioactivity, radiation is emitted from an unstable nucleus. This radiation can take various forms like alpha particles, beta particles, or gamma rays. These particles or rays are emitted as a result of the unstable nucleus's attempt to achieve a more stable configuration. Therefore, the correct answer is radiation (Choice C). Electrons (Choice A), protons (Choice B), and neutrons (Choice D) are not typically emitted during radioactivity, as the emission is primarily in the form of radiation.
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