HESI A2
HESI A2 Chemistry Questions
1. What is the mass number of an atom with 6 protons, 6 neutrons, and 6 electrons?
- A. 12
- B. 18
- C. 6
- D. 8
Correct answer: A
Rationale: The mass number of an atom is the sum of protons and neutrons. In this case, the atom has 6 protons and 6 neutrons, thus the mass number is 6 + 6 = 12. Therefore, choice A (12) is the correct answer. Choices B (18), C (6), and D (8) are incorrect because the mass number is determined by the sum of protons and neutrons, not the number of electrons or a different combination of particles.
2. What happens in a single displacement reaction?
- A. A compound decomposes into two substances.
- B. An active element displaces a less active element.
- C. A precipitate solid forms from the reaction of two solutions.
- D. The oxidation states of atoms in the reactants change.
Correct answer: B
Rationale: In a single displacement reaction, an active element displaces a less active element in a compound. This process involves one element replacing another in a compound, resulting in the formation of a new compound. Option A is incorrect because a single displacement reaction does not involve the decomposition of a compound into two substances. Option C is incorrect because it describes a precipitation reaction, not a single displacement reaction. Option D is incorrect because it describes oxidation-reduction reactions, not specifically single displacement reactions.
3. What is the name of the device that separates gaseous ions by their mass-to-charge ratio?
- A. mass spectrometer
- B. interferometer
- C. magnetometer
- D. capacitance meter
Correct answer: A
Rationale: A mass spectrometer is a device specifically designed to separate gaseous ions based on their mass-to-charge ratio. This separation process involves ionization, acceleration of the sample, and the deflection of ions in a magnetic field according to their mass-to-charge ratio. The other options, 'interferometer,' 'magnetometer,' and 'capacitance meter,' do not perform the specific function of separating gaseous ions based on their mass-to-charge ratio, making them incorrect choices.
4. Which type of radiation involves the emission of helium ions?
- A. Beta
- B. Alpha
- C. Gamma
- D. Delta
Correct answer: B
Rationale: Alpha radiation involves the emission of helium ions. Helium ions are composed of two protons and two neutrons, which is the same as the nucleus of a helium atom. This type of radiation has low penetration power and can be stopped by a piece of paper or human skin, making it less harmful compared to other forms of radiation like beta or gamma radiation. Beta radiation involves the emission of high-speed electrons, while gamma radiation involves electromagnetic waves with high energy. Delta radiation is not a recognized form of radiation in this context, making it an incorrect choice.
5. Which element would you expect to be least reactive?
- A. Li
- B. Cr
- C. Nd
- D. Xe
Correct answer: D
Rationale: Xenon (Xe) is a noble gas located in Group 18 of the periodic table. Noble gases are known for their stable and unreactive nature due to having a full outer shell of electrons. Therefore, xenon would be expected to be the least reactive among the given elements. Choice A (Li) is a metal in Group 1 of the periodic table, which tends to be reactive, especially with water. Choice B (Cr) is a transition metal known for its reactivity in some forms. Choice C (Nd) is a rare earth element, which can exhibit varying reactivity depending on the compound or environment.
Similar Questions
Access More Features
HESI A2 Basic
$49/ 30 days
- 3,000 Questions with answers
- 30 days access
HESI A2 Premium
$99/ 90 days
- Actual HESI A2 Questions
- 3,000 questions with answers
- 90 days access