what does the term amphoteric mean

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. What type of chemical reaction is represented by AB â†’ A + B?

A. Synthesis
B. Decomposition
C. Single replacement
D. Double replacement

Correct answer: B

Rationale: The chemical equation AB â†’ A + B represents a decomposition reaction. In a decomposition reaction, a single compound breaks down into two or more simpler substances. In this specific reaction, compound AB is decomposed into its elements, A and B, making it a decomposition reaction. Choice A, Synthesis, involves the combination of two or more substances to form a more complex product, which is not the case here. Choices C and D, Single replacement and Double replacement, involve the exchange of ions between compounds or elements, which is not happening in the given reaction.

3. What type of chemical reaction involves the reaction of a compound with oxygen?

A. Decomposition
B. Synthesis
C. Combustion
D. Single replacement

Correct answer: C

Rationale: The correct answer is C: Combustion. A combustion reaction is characterized by a compound reacting with oxygen. During this process, heat and light are often produced as energy is released in the form of heat. Combustion is a common type of reaction involving organic compounds, like hydrocarbons, reacting with oxygen to produce carbon dioxide and water. Choices A, B, and D are incorrect because decomposition involves a compound breaking down into simpler substances, synthesis involves the combination of two or more substances to form a more complex one, and single replacement involves an element replacing another element in a compound.

4. What is the correct electron configuration for lithium?

A. 1sÂ²2sÂ¹
B. 1sÂ²2sÂ²
C. 1sÂ²2sÂ¹2pÂ¹
D. 1sÂ¹2sÂ¹2pÂ²

Correct answer: A

Rationale: The electron configuration for lithium is 1sÂ²2sÂ¹. Lithium has 3 electrons, and the configuration indicates that the first two electrons fill the 1s orbital, while the third electron fills the 2s orbital. Therefore, the correct electron configuration for lithium is 1sÂ²2sÂ¹. Choice B (1sÂ²2sÂ²) is incorrect as it represents the electron configuration for beryllium, not lithium. Choice C (1sÂ²2sÂ¹2pÂ¹) includes the 2p orbital, which is not involved in lithium's electron configuration. Choice D (1sÂ¹2sÂ¹2pÂ²) is incorrect as it does not accurately represent lithium's electron configuration.

5. 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.