HESI A2
HESI A2 Chemistry Questions
1. What is the name of the negatively charged subatomic particles?
- A. Protons
- B. Neutrons
- C. Electrons
- D. Isotopes
Correct answer: C
Rationale: The correct answer is C: Electrons. Electrons are the negatively charged subatomic particles. They are found outside the atomic nucleus and carry a negative charge. Protons are positively charged particles found in the nucleus, neutrons have no charge, and isotopes are atoms of the same element with different numbers of neutrons, not subatomic particles.
2. Which chemical reaction involves the breaking of a compound into its components?
- A. Decomposition reaction
- B. Combustion reaction
- C. Neutralization reaction
- D. Single displacement reaction
Correct answer: A
Rationale: The correct answer is A: Decomposition reaction. A decomposition reaction involves breaking down a compound into its components. During this reaction, a single compound breaks down into two or more simpler substances. This process is the opposite of a synthesis reaction where multiple substances combine to form a more complex compound. Choices B, C, and D are incorrect because combustion reaction involves burning a substance in oxygen, neutralization reaction involves the reaction between an acid and a base to form water and a salt, and single displacement reaction involves an element displacing another in a compound.
3. What are the two types of chemical bonding?
- A. Covalent & hydrogen
- B. Ionic & covalent
- C. Ionic & hydrogen
- D. Covalent & metallic
Correct answer: B
Rationale: The correct answer is B: Ionic & covalent. Ionic bonding involves the transfer of electrons between atoms, resulting in the formation of positive and negative ions attracted to each other. Covalent bonding involves the sharing of electrons between atoms to achieve a stable electron configuration. Choice A is incorrect as hydrogen bonding is a type of intermolecular force, not a primary type of chemical bonding. Choice C is incorrect as hydrogen bonding is not a primary type of chemical bonding. Choice D is incorrect as metallic bonding involves the sharing of electrons in a 'sea of electrons' within a metal lattice, not covalent bonding.
4. What is the correct formula for iron III oxide?
- A. IO
- B. FeS
- C. Fe₂O₃
- D. OFe₂₃
Correct answer: C
Rationale: The correct formula for iron III oxide is Fe2O3. In this formula, Fe represents iron and O represents oxygen. Iron III oxide consists of two iron (Fe) ions combined with three oxygen (O) ions. Thus, the correct formula is Fe2O3. Choice A (IO) is incorrect as it does not represent the correct combination of iron and oxygen ions. Choice B (FeS) is incorrect as it represents iron sulfide, not iron III oxide. Choice D (OFe₂₃) is incorrect as it does not follow the correct chemical nomenclature for iron III oxide.
5. What is a balanced equation?
- A. A description where reactants and products are not equal
- B. An equation where the number of each type of atom is the same on both sides
- C. A chemical formula showing only reactants
- D. An equation without coefficients
Correct answer: B
Rationale: A balanced equation is one where the number of each type of atom is the same on both sides, fulfilling the law of conservation of mass. This principle ensures that the total number of atoms of each element is equal in both reactants and products, signifying that no atoms are created or destroyed, but rather rearranged. Choice A is incorrect because a balanced equation has equal numbers of atoms in the reactants and products. Choice C is incorrect as a balanced equation includes both reactants and products. Choice D is incorrect because coefficients are essential in balancing equations by adjusting the number of atoms present.
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