Free HESI A2 Chemistry practice for HESI A2 Chemistry Version 1 (HESI A2). Answer 23 nursing exam-style questions with rationales, exam mode, and progress track
What is the correct name for aqueous HI?
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Explanation:
The correct name for aqueous HI is hydroiodic acid. In the naming of binary acids, the prefix 'hydro-' is combined with the root of the nonmetal element and the suffix '-ic acid'. Therefore, the correct systematic name for HI in aqueous solution is hydroiodic acid.
What is the name for the horizontal rows of the periodic table?
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Explanation:
In the periodic table, the horizontal rows are called 'periods.' These periods represent the number of electron shells an element has. Each period starts a new energy level, indicating the elements' properties and atomic structure. 'Groups' refer to the vertical columns of the periodic table, each containing elements with similar chemical properties. 'Families' can also be used interchangeably with groups. 'Sets' is a vague term and not specifically related to the layout of the periodic table. Understanding the distinction between 'periods' and 'groups' is crucial in comprehending the organization and properties of elements in the periodic table.
What is a benefit of water's ability to make hydrogen bonds?
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Explanation:
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.
What are bases or alkaline solutions known as?
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Explanation:
Bases or alkaline solutions are substances that can accept protons (H+ ions), making them hydrogen acceptors. When a base reacts with an acid, it accepts a proton to form water, hence neutralizing the acid. This property distinguishes bases from acids, which donate protons (H+ ions). Therefore, the correct answer is that bases or alkaline solutions are known as hydrogen acceptors.
How can water be boiled at room temperature?
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Explanation:
Water boils when its vapor pressure equals the atmospheric pressure. By increasing the pressure, the atmospheric pressure is reached at a lower temperature, allowing water to boil at room temperature. This phenomenon is utilized in specific scenarios such as high-altitude cooking where the reduced atmospheric pressure requires an increase in the boiling point to cook food properly. Therefore, the correct answer is by increasing the pressure.
What is 119 K in degrees Celsius?
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Explanation:
To convert from Kelvin to Celsius, you subtract 273.15 from the temperature in Kelvin. Therefore, 119 K - 273.15 = -154C. Hence, 119 K is equivalent to -154C. The correct answer is -154C, as it results from the conversion formula from Kelvin to Celsius.
What is the SI unit of energy?
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Explanation:
The correct answer is B: joule. The joule is the SI unit of energy, defined as the work done by a force of one newton acting over a distance of one meter. It is extensively used to measure energy in various fields such as physics, chemistry, and engineering.
What is the name of the device that separates gaseous ions by their mass-to-charge ratio?
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Explanation:
The correct answer is a mass spectrometer. A mass spectrometer is a device specifically designed to separate gaseous ions based on their mass-to-charge ratio. The separation occurs as ions pass through the mass spectrometer, allowing for the identification and quantification of compounds present in a sample. This analytical instrument is widely used in chemistry and other scientific fields due to its ability to provide detailed information about the composition of substances.
Which material has the smallest specific heat capacity?
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Explanation:
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.
Which of the following describes atomic mass?
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Explanation:
The correct answer is C: Average mass of that element's isotopes. Atomic mass is the weighted average mass of the isotopes of an element, considering the natural abundance of each isotope. It is not just the sum of protons and neutrons or neutrons and electrons. Understanding atomic mass is crucial in chemistry as it helps in determining the molar mass of elements, which is essential in various chemical calculations such as stoichiometry and reaction equations.
What is the name for a reaction in which electrons are transferred from one atom to another?
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Explanation:
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.
What are van der Waals forces?
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Explanation:
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.
What is the term for the number of protons in an atom?
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Explanation:
The term for the number of protons in an atom is the atomic number. The atomic number is a fundamental property of an element, representing the number of protons in an atom's nucleus. It serves as the unique identity of an element and determines its position on the periodic table and its chemical behavior. Atomic mass refers to the average mass of an atom, including protons, neutrons, and electrons, while atomic weight is the average weight of an element considering the abundance of its isotopes. 'Atomic identity' is not a standard term in chemistry to describe the number of protons in an atom, making option D, 'atomic number,' the correct answer.
Which of the following elements is an alkali metal?
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Explanation:
Rubidium is the correct answer because alkali metals are found in Group 1 of the periodic table. Rubidium is located in Group 1 and exhibits properties typical of alkali metals, such as low melting points, high reactivity, and the tendency to form ionic compounds. Magnesium is an alkaline earth metal, hydrogen is a nonmetal, and chlorine is a halogen, so they do not belong to the alkali metal group.
What can be predicted by using the periodic table?
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Explanation:
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.
What is a combustion reaction?
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Explanation:
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.
What type of reaction is represented by the equation KCl --> K + Cl₂?
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Explanation:
The reaction KCl --> K + Cl2 is an example of a decomposition reaction. In a decomposition reaction, a compound breaks down into its constituent elements or simpler compounds. In this case, potassium chloride (KCl) decomposes into potassium (K) and chlorine gas (Cl2). Therefore, the correct answer is B, Decomposition.
Chemical reactions in living systems proceed along catabolic pathways, and there tends to be an increase in which of the following?
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Explanation:
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.
What is the pH of a solution with a pH of 7?
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Explanation:
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.
What does the term 'atomic number' represent?
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Explanation:
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).
What is the charge on potassium in the compound KCl?
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Explanation:
In the compound KCl, the overall charge must be zero since it is a neutral compound. Chlorine (Cl) typically has a charge of -1 in ionic compounds. Therefore, for the compound to be neutral, potassium (K) must have a charge of +1 to balance the -1 charge of chlorine. This results in a total charge of 0 for the compound. Thus, the correct answer is +1. The positively charged potassium ion (K+) combines with the negatively charged chloride ion (Cl-) to form an electrically neutral compound, potassium chloride (KCl).
Which of the following could be an empirical formula?
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Explanation:
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.
What is the term for the reactant that is entirely consumed by the reaction?
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Explanation:
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.
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