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: A

Rationale: Statement A is correct. pH is a measure of the effective concentration of hydrogen ions in a solution, and it is related to the molarity of H+ by the formula pH = - log [H+]. This equation illustrates the logarithmic relationship between pH and the concentration of hydrogen ions. Oxygen ions and hydrogen atoms are not directly related to pH in the same manner as hydrogen ions. Acidity is determined by the concentration of hydrogen ions in a solution, and this concentration is what pH measures. Therefore, option A is the only statement that correctly defines the relationship between pH and the concentration of hydrogen ions in a solution. Choices B, C, and D are incorrect as they provide inaccurate information about the relationship between pH and the ions/atoms mentioned. Option B incorrectly associates pH with oxygen ions, option C mentions hydrogen atoms instead of hydrogen ions, and option D confuses acidity with pH, which is a measure of hydrogen ion concentration, not molarity.

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.

Correct Answer: D

Rationale: A. The solubility of a substance is indeed defined as the concentration of a solute that can be dissolved in a solvent to form a saturated solution at a specific temperature and pressure. B. Substances with solubilities much less than 1 g/100 mL of solvent are generally considered insoluble because they do not dissolve in significant amounts in the solvent. C. A saturated solution is one that cannot dissolve any more solute as it has reached its maximum capacity at a specific temperature and pressure. Therefore, all the statements provided are correct, making option D the correct answer.