HESI A2
HESI A2 Chemistry Practice Test
1. What does the term amphoteric mean?
- A. A substance that only acts as a base
- B. A substance that can act as both a base and an acid
- C. A substance that only acts as an acid
- D. A substance that acts as neither a base nor an acid
Correct answer: B
Rationale: The term 'amphoteric' refers to substances that have the ability to act as both acids and bases depending on the surrounding conditions. This dual nature allows amphoteric substances to donate or accept protons, making them versatile in various chemical reactions. Choice A is incorrect because amphoteric substances can also act as acids. Choice C is incorrect as amphoteric substances can also act as bases. Choice D is incorrect as amphoteric substances can act as either a base or an acid.
2. Arsenic and silicon are examples of ___________.
- A. metals
- B. nonmetals
- C. metalloids
- D. heavy metals
Correct answer: C
Rationale: Arsenic and silicon are both examples of metalloids. Metalloids have properties that lie between those of metals and nonmetals. They exhibit characteristics of both groups, making them versatile elements with various applications in different industries. Choice A (metals) is incorrect as arsenic and silicon do not exhibit typical metallic properties. Choice B (nonmetals) is incorrect as they do not possess all the properties of nonmetals. Choice D (heavy metals) is incorrect as heavy metals refer to a different group of elements with high atomic weights, and arsenic and silicon are not categorized as heavy metals.
3. What are the three types of radiation?
- A. Alpha, beta, gamma
- B. Alpha, beta, delta
- C. Gamma, delta, epsilon
- D. Beta, gamma, epsilon
Correct answer: A
Rationale: The correct answer is Alpha, beta, gamma. Alpha radiation consists of helium nuclei, beta radiation comprises electrons or positrons, and gamma radiation is high-energy electromagnetic radiation. Choice B, delta, is incorrect as delta is not a type of radiation. Choice C, gamma, delta, epsilon, and Choice D, beta, gamma, epsilon, are incorrect as they do not include the three standard types of radiation.
4. 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.
5. What type of bond is present in sodium chloride?
- A. Covalent
- B. Ionic
- C. Metallic
- D. Hydrogen
Correct answer: B
Rationale: Ionic bonds are found in sodium chloride. In an ionic bond, one atom donates an electron to another atom, resulting in the formation of positively and negatively charged ions that are held together by electrostatic forces of attraction. Sodium chloride is a classic example of an ionic compound, where sodium (Na) donates an electron to chlorine (Cl), forming Na+ and Cl- ions that are attracted to each other, creating a crystal lattice structure. Covalent bonds involve the sharing of electron pairs between atoms, which is not the case in sodium chloride. Metallic bonds occur in metals where electrons are delocalized and shared across a lattice, unlike the specific transfer seen in ionic bonds. Hydrogen bonds are a type of intermolecular force, not the primary bond type present in sodium chloride.
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