HESI A2
HESI A2 Version 1 Chemistry Questions
Question 1 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.
Question 2 of 5
Which of the following could be an empirical formula?
Correct Answer: C
Rationale: An empirical formula represents the simplest whole-number ratio of atoms in a compound. For a hydrocarbon compound consisting of carbon and hydrogen, the empirical formula should have the simplest ratio of carbon to hydrogen. Choice C, 'CH,' is the correct empirical formula as it represents a 1:1 ratio of carbon to hydrogen atoms, indicating the simplest ratio. Choices A, B, and D have multiple atoms of carbon and hydrogen, which do not represent the simplest whole-number ratio. Therefore, 'CH' is the empirical formula that best fits the definition.
Question 3 of 5
What is the term for the reactant that is fully consumed by the reaction?
Correct Answer: A
Rationale: The correct answer is 'limiting reactant.' In a chemical reaction, the limiting reactant is the substance that is entirely consumed when the reaction proceeds. It determines the extent of the reaction and limits the amount of product that can be formed. The other choices, such as 'reducing agent,' 'reaction intermediate,' and 'reagent,' do not specifically refer to the reactant that is fully consumed in the reaction.
Question 4 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 5 of 5
What can be predicted using the periodic table?
Correct Answer: A
Rationale: The periodic table serves as a fundamental tool in chemistry, organizing elements based on their atomic number, electron configuration, and recurring chemical properties. Through the arrangement of elements, one can predict various properties of each element. Periodic trends such as atomic radius, electronegativity, and ionization energy allow for the anticipation of element characteristics like reactivity, boiling point, and other physical and chemical properties. Hence, the correct answer is A: The properties of each of the elements can be successfully predicted using the periodic table.