HESI A2 Version 1 Chemistry

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).

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.

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.

Correct Answer: B

Rationale: 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.