HESI A2
HESI A2 Chemistry Practice Test
1. At what temperature does water boil in °F?
- A. 210°F
- B. 212°F
- C. 215°F
- D. 220°F
Correct answer: B
Rationale: Water boils at 212°F under standard atmospheric pressure. This is the point at which water changes from a liquid to a gas phase. Choice A (210°F) is incorrect as it is below the boiling point of water. Choice C (215°F) and Choice D (220°F) are also incorrect as they are above the boiling point of water.
2. What is the charge of a beta particle?
- A. -1
- B. +1
- C. +2
- D. No charge
Correct answer: A
Rationale: A beta particle has a charge of -1. Beta particles are high-energy, high-speed electrons emitted during radioactive decay processes. Since electrons carry a charge of -1, beta particles also carry a charge of -1. This negative charge indicates that beta particles are negatively charged. Option B is incorrect as it suggests a positive charge, which is not the case for beta particles. Option C is incorrect as it indicates a higher positive charge, which is not true for beta particles. Option D is incorrect as beta particles do have a charge, which is negative.
3. The three important allotropic forms of phosphorus are red, white, and ___________.
- A. green
- B. gray
- C. black
- D. silver
Correct answer: C
Rationale: The three important allotropic forms of phosphorus are red, white, and black. These forms indicate the different physical properties and reactivity of phosphorus under various conditions. Red phosphorus is more stable and less reactive than white phosphorus, while black phosphorus is the least reactive form. Choice C, 'black,' is the correct answer as it completes the sequence of allotropic forms of phosphorus. Choices A, 'green,' B, 'gray,' and D, 'silver,' are incorrect as they do not represent recognized forms of phosphorus.
4. 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.
5. What does the mass number minus the atomic number equal?
- A. Number of electrons
- B. Number of neutrons
- C. Number of protons
- D. Number of isotopes
Correct answer: B
Rationale: The mass number of an atom represents the total number of protons and neutrons in its nucleus. The atomic number indicates the number of protons in the nucleus. The difference between the mass number and the atomic number provides the number of neutrons present in the nucleus of an atom. Therefore, mass number minus atomic number equals the number of neutrons. Choice A is incorrect because the number of electrons is not determined by the mass number and atomic number. Choice C is incorrect as it represents the number of protons, not the difference between the mass number and atomic number. Choice D is incorrect as isotopes refer to atoms of the same element with different numbers of neutrons, not the difference between mass number and atomic number.
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