HESI A2
HESI A2 Version 1 Chemistry Questions
Question 1 of 5
What is the name of a reaction in which electrons are transferred from one atom to another?
Correct Answer: C
Rationale: A redox reaction, short for reduction-oxidation reaction, involves the transfer of electrons from one reactant to another. In these reactions, one substance is oxidized (loses electrons) while another is reduced (gains electrons). The term 'redox' comes from the simultaneous occurrence of reduction and oxidation reactions. 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, with no mention of electron transfer. Double-displacement reaction (choice D) involves an exchange of ions between two compounds but does not specifically involve electron transfer between atoms. Therefore, option C, redox reaction, is the correct answer as it accurately describes the electron transfer process that occurs during such reactions.
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 is a benefit of water's ability to make hydrogen bonds?
Correct Answer: D
Rationale: The correct answer is D - High specific heat. Water's ability to make hydrogen bonds leads to a high specific heat capacity, which allows it to absorb and release large amounts of heat with minimal temperature change. This property is crucial for maintaining stable temperatures in living organisms and aquatic environments. High specific heat helps regulate body temperature in organisms and prevents sudden temperature fluctuations in water bodies, providing an essential benefit for various biological processes.
Question 4 of 5
What is a combustion reaction?
Correct Answer: D
Rationale: A combustion reaction is a type of chemical reaction that involves a substance reacting with oxygen gas to produce heat and light. This reaction is exothermic, releasing energy in the form of heat and light. The correct answer is D because combustion reactions specifically involve oxygen as a reactant, leading to the production of heat and light as byproducts.
Question 5 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.