HESI A2
HESI A2 Version 1 Chemistry Questions
Question 1 of 5
What is the pH of a solution with a pH of 7?
Correct Answer: C
Rationale: The correct answer is C: Neutral. A pH of 7 is considered neutral on the pH scale, which ranges from 0 to 14. A pH of 7 indicates a balance between acidic and basic properties in a solution, making it neither acidic nor basic. Values below 7 are acidic, above 7 are basic, and 7 is the midpoint representing neutrality. Therefore, a solution with a pH of 7 is neutral.
Question 2 of 5
What does the term 'atomic number' represent?
Correct Answer: B
Rationale: The atomic number represents the number of protons in the nucleus of an atom. This number uniquely identifies an element and determines its placement in the periodic table. The number of neutrons and electrons can vary among different isotopes of an element, but the number of protons remains constant, defining the element's atomic number. Therefore, the correct answer is the number of protons (Choice B).
Question 3 of 5
Which material has the smallest specific heat capacity?
Correct Answer: C
Rationale: Specific heat capacity refers to the amount of heat energy needed to raise the temperature of a substance by a certain amount. In this context, aluminum has the smallest specific heat capacity among the materials listed. This means that aluminum requires the least amount of heat energy to increase its temperature compared to water, wood, and glass. As a result, aluminum is the material with the smallest specific heat capacity in this scenario.
Question 4 of 5
What is the name for a reaction in which electrons are transferred from one atom to another?
Correct Answer: C
Rationale: A redox reaction, also known as a reduction-oxidation reaction, involves the transfer of electrons from one substance to another. During this process, one substance is oxidized (loses electrons) while another is reduced (gains electrons). This transfer of electrons is a key characteristic of redox reactions, making choice C the correct answer. Combustion reaction (choice A) involves a substance reacting with oxygen to produce heat and light, but it does not necessarily involve electron transfer. Synthesis reaction (choice B) involves the combination of two or more substances to form a new compound, without necessarily involving electron transfer. Double-displacement reaction (choice D) involves the exchange of ions between two compounds, but not the transfer of electrons from one atom to another.
Question 5 of 5
What are van der Waals forces?
Correct Answer: A
Rationale: Van der Waals forces are weak intermolecular forces that occur between non-polar molecules. These forces result from temporary fluctuations in electron distribution within the molecules, leading to slight positive and negative charges. This results in weak attraction between molecules through van der Waals forces. Hydrogen bonds, in contrast, are stronger intermolecular forces that specifically occur between molecules containing hydrogen bonded to a highly electronegative atom like oxygen or nitrogen. Conjugal bonds do not exist in chemistry and are not relevant to intermolecular forces.