HESI A2
HESI A2 Version 1 Chemistry Questions
Question 1 of 5
What is the atomic number?
Correct Answer: B
Rationale: The atomic number is the number of protons in an atom's nucleus. It uniquely identifies an element and determines its chemical properties. The number of neutrons and electrons can vary in an atom, but the number of protons remains constant for a specific element. Therefore, the correct answer is the 'Number of protons' (Choice B).
Question 2 of 5
Which of the following elements does not exist as a diatomic molecule?
Correct Answer: A
Rationale: The correct answer is boron (A). Diatomic molecules consist of two atoms of the same element bonded together. Boron does not naturally form diatomic molecules in its elemental state. Fluorine (Fā‚‚), oxygen (Oā‚‚), and nitrogen (Nā‚‚) are examples of elements that exist as diatomic molecules in their elemental forms. Boron typically forms covalent bonds with other elements but does not naturally exist as a diatomic molecule.
Question 3 of 5
What can be predicted by using the periodic table?
Correct Answer: A
Rationale: The periodic table is a fundamental tool in chemistry that organizes elements based on their properties. By using the periodic table, scientists can predict the properties of each element. The arrangement of elements in the table groups together elements with similar characteristics, allowing for the prediction of various properties such as reactivity, atomic size, and electronegativity. These predictions are possible because elements in the same group or period exhibit similar chemical behaviors. Therefore, the correct answer is A: The properties of each of the elements.
Question 4 of 5
Chemical reactions in living systems proceed along catabolic pathways, and there tends to be an increase in which of the following?
Correct Answer: A
Rationale: In catabolic pathways, complex molecules are broken down into simpler ones, leading to an increase in disorder or entropy. Entropy represents the measure of randomness or disorder in a system. As chemical reactions break down molecules, the overall disorder in the system tends to increase, making entropy the correct answer in this context. Therefore, the correct answer is 'Entropy' as it aligns with the concept of increased disorder in catabolic pathways. Enthalpy, on the other hand, relates to the total heat content of a system and is not specifically associated with disorder or complexity. Glucose and glycogen are molecules involved in energy storage and are not directly related to the increase in disorder observed in catabolic pathways.
Question 5 of 5
What is the term for the reactant that is entirely consumed by the reaction?
Correct Answer: A
Rationale: The correct answer is A, limiting reactant. In a chemical reaction, the limiting reactant is the substance that is entirely consumed when the reaction reaches completion. It determines the maximum amount of product that can be formed. The reducing agent (choice B) is a substance that donates electrons to another chemical species, the reaction intermediate (choice C) is a molecule formed and consumed in different steps of the reaction, and a reagent (choice D) is a general term for any substance participating in a chemical reaction.