HESI A2
HESI A2 Chemistry Questions
1. Which material has the smallest specific heat capacity?
- A. water
- B. wood
- C. aluminum
- D. glass
Correct answer: C
Rationale: Specific heat capacity is the amount of heat required to raise the temperature of a unit mass of a substance by one degree Celsius. Among the options provided, aluminum has the smallest specific heat capacity. This means that it requires the least amount of heat to raise its temperature compared to water, wood, and glass. Water has a high specific heat capacity, making it resistant to temperature changes, while wood and glass have higher specific heat capacities compared to aluminum.
2. What is a benefit of water's ability to make hydrogen bonds?
- A. Lack of cohesiveness
- B. Low surface tension
- C. Use as a nonpolar solvent
- D. High specific heat
Correct answer: D
Rationale: The correct answer is D, high specific heat. Water's ability to form hydrogen bonds results in a high specific heat capacity, allowing it to absorb and release a large amount of heat energy with minimal temperature change. This property is essential for moderating temperature changes in organisms and maintaining stable environmental conditions for life processes. Choices A, lack of cohesiveness, and C, use as a nonpolar solvent, are incorrect. Water actually has high cohesiveness due to its ability to form hydrogen bonds, and it is a polar solvent, not nonpolar. Choice B, low surface tension, is also incorrect as water's hydrogen bonding contributes to its relatively high surface tension.
3. What term is used to describe the emission of particles from an unstable nucleus?
- A. Radioactivity
- B. Radiation
- C. Decay
- D. Fusion
Correct answer: A
Rationale: Radioactivity is the term used to describe the emission of particles from an unstable nucleus. When a nucleus is unstable, it undergoes radioactive decay by emitting particles such as alpha or beta particles. This process releases energy and transforms the unstable nucleus into a more stable configuration. Choice B, 'Radiation,' is a broad term that encompasses various forms of energy emitted from a source; it is not specific to the emission from an unstable nucleus. Choice C, 'Decay,' is closely related but doesn't specifically indicate the emission of particles from an unstable nucleus. Choice D, 'Fusion,' refers to the process of combining nuclei to form a heavier nucleus, not the emission of particles from an unstable nucleus.
4. What is the charge of an alpha particle?
- A. -1
- B. +1
- C. +2
- D. No charge
Correct answer: C
Rationale: An alpha particle consists of two protons and two neutrons, resulting in a total charge of +2 due to the presence of two positively charged protons. Therefore, the correct answer is C, indicating a charge of +2. Choices A, B, and D are incorrect because an alpha particle is positively charged due to the two protons it contains, resulting in a charge of +2.
5. What is the correct name of ZnSOâ‚„?
- A. Zinc sulfate
- B. Zinc sulfide
- C. Zinc sulfur
- D. Zinc oxide
Correct answer: A
Rationale: The correct name of ZnSOâ‚„ is zinc sulfate. In this compound, zinc is combined with the polyatomic ion sulfate (SOâ‚„). Sulfate is a common anion formed from sulfur and oxygen atoms. Therefore, the correct name for ZnSOâ‚„ is zinc sulfate. Choice B, Zinc sulfide, is incorrect because sulfide is a different anion (S²â») compared to sulfate (SO₄²â»). Choice C, Zinc sulfur, is incorrect as it does not represent the correct anion in the compound. Choice D, Zinc oxide, is incorrect as it involves an oxygen anion, not sulfate.
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