Correct Answer: C

Rationale: The correct answer is the Ideal Gas Law (Choice C). The ideal gas law, PV = nRT, describes the relationship between pressure (P), volume (V), temperature (T), and the number of moles of gas (n) for an ideal gas. It states that the product of pressure and volume is directly proportional to the absolute temperature of the gas when the number of moles is held constant. This law is a fundamental principle in understanding the behavior of ideal gases. Choices A, B, and D are incorrect. The Law of conservation of energy (Choice A) pertains to the principle that energy cannot be created or destroyed; Newton's laws of motion (Choice B) describe the relationship between the motion of an object and the forces acting on it; Archimedes' principle (Choice D) deals with the buoyant force exerted on an object immersed in a fluid. These principles are not directly related to the relationship between pressure, volume, and temperature for ideal gases.

Correct Answer: B

Rationale: Lymphedema is a chronic condition that occurs when lymph vessels become blocked, leading to swelling and fluid retention in the affected area. Inflammation of lymph nodes, spleen malfunction, or decreased bone marrow production are not directly associated with the development of lymphedema. Lymph vessels play a crucial role in carrying lymphatic fluid, and when they are blocked, it disrupts the normal flow of fluid, resulting in lymphedema. Therefore, the correct answer is that lymphedema occurs when lymph vessels become blocked.

Correct Answer: B

Rationale: In the balanced chemical equation for the combustion of methane, CH₄ + 2O₂ → CO₂ + 2H₂O, the coefficient of oxygen (O₂) is 2. This indicates that two molecules of oxygen are required to react with one molecule of methane to produce carbon dioxide and water, ensuring the equation is balanced. Choice A is incorrect because the coefficient of oxygen is not 1 but 2. Choices C and D are incorrect as they do not represent the correct coefficient of oxygen in the balanced equation. Understanding the coefficients in a balanced chemical equation is crucial for accurately representing the stoichiometry of the reaction.

Correct Answer: C

Rationale: Lymph moves through the lymphatic vessels primarily due to muscle contractions and breathing movements and also with the help of one-way valves within the vessels. The lymphatic system lacks a central pump like the heart; hence, it relies on the contraction of surrounding muscles and breathing movements to propel lymph fluid. One-way valves within the lymphatic vessels prevent backflow and ensure the unidirectional flow of lymph. Option A is incorrect as the lymphatic system does not rely on the pumping action of the heart. Option D is incorrect as the correct answer is the combination of muscle contractions, breathing movements, and one-way valves, not all the options provided.

Correct Answer: C

Rationale: The medullary cavity is the correct answer. It is the central cavity within the shafts of long bones where red bone marrow is located, responsible for the production of red blood cells. The periosteum is the outer layer of bone that provides nourishment and participates in bone repair. The diaphysis refers to the shaft of a long bone that contains yellow bone marrow. The epiphysis is the end of a long bone involved in joint articulation and contains red bone marrow in children for blood cell production.