HESI A2 Chemistry Practice Test - Nurselytic

Correct Answer: A

Rationale: Different isotopes of a particular element contain the same number of protons. Isotopes are defined by the number of neutrons they have, which can vary while the number of protons remains the same. This is because the number of protons in an atom determines its elemental identity.
Choice B - Neutrons is incorrect because isotopes can have different numbers of neutrons.
Choice C - Protons and neutrons is incorrect because the number of neutrons can vary in isotopes.
Choice D - Protons, neutrons, and electrons is incorrect because electrons are not fixed and can vary in an atom, but the number of protons is what defines the element.

Correct Answer: B

Rationale: A balanced equation is one where the number of each type of atom is the same on both sides, fulfilling the law of conservation of mass. This principle ensures that the total number of atoms of each element is equal in both reactants and products, signifying that no atoms are created or destroyed, but rather rearranged.
Choice A is incorrect because a balanced equation has equal numbers of atoms in the reactants and products.
Choice C is incorrect as a balanced equation includes both reactants and products.
Choice D is incorrect because coefficients are essential in balancing equations by adjusting the number of atoms present.

Correct Answer: D

Rationale: Boyle's law describes the relationship between the pressure and volume of an ideal gas when the temperature and amount of gas are constant. According to Boyle's law, if the pressure of a gas increases, its volume decreases proportionally, and vice versa. This law is expressed by the equation P1V1 = P2V2, where P1 and V1 represent the initial pressure and volume, while P2 and V2 represent the final pressure and volume when the temperature and amount of gas remain unchanged. Understanding Boyle's law is essential in comprehending the behavior of gases under varying conditions and is fundamental in the study of thermodynamics.

The other choices are incorrect:
- Henry's law deals with the solubility of gases in liquids, not the relationship between pressure and volume of gases.
- Dalton's law states that the total pressure exerted by a mixture of gases is equal to the sum of the partial pressures of individual gases, not the pressure-volume relationship.
- Brown's law is a fabricated concept and does not exist in the context of gas laws.

Correct Answer: A

Rationale: In the periodic table, the elements are arranged in order of increasing atomic number. This organization is based on the number of protons in the nucleus of each element. It provides a systematic way to classify elements and predict their properties. Knowing the atomic number of an element helps determine its placement in the periodic table and its characteristics.
Therefore, the correct answer is the order of increasing atomic number as it is fundamental to the structure and properties of the elements.

Choices B, C, and D are incorrect. Alphabetical order does not reflect any underlying property of the elements, metallic properties vary across the table, and neutron content alone is not the basis for the arrangement in the periodic table.

Correct Answer: B

Rationale: There are 20 essential amino acids required for human life. These amino acids cannot be synthesized by the body and must be obtained through the diet. They play crucial roles in various physiological functions and are necessary for protein synthesis and overall health.
Choice A is incorrect because there are not 22 essential amino acids.
Choice C is incorrect as there are more than 18 essential amino acids.
Choice D is incorrect as there are not 24 essential amino acids for human life.