HESI A2
HESI A2 Version 1 Chemistry Questions
Question 1 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 2 of 5
What is the name for the horizontal rows of the periodic table?
Correct Answer: B
Rationale: 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.
Question 3 of 5
Which of the following elements is an alkali metal?
Correct Answer: B
Rationale: 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.
Question 4 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 5 of 5
How can water be boiled at room temperature?
Correct Answer: B
Rationale: 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.