Correct Answer: C

Rationale: The correct answer is C: 'Energy can neither be created nor destroyed, only transformed from one form to another.' The law of conservation of energy is a fundamental principle in physics. It states that the total energy in a closed system remains constant over time. Energy can change from one form to another (e.g., potential energy to kinetic energy), but the total amount of energy remains the same. Choices A, B, and D are incorrect because they do not accurately represent the law of conservation of energy. Energy is not created or destroyed according to this law, but rather transformed.

Correct Answer: B

Rationale: The thyroid gland, located in the neck, is responsible for regulating metabolism, growth, and development. It produces hormones such as thyroxine (T4) and triiodothyronine (T3) that play a crucial role in these functions. The parathyroid gland regulates calcium levels, the pituitary gland controls various hormonal functions, and the thymus gland is involved in immune system development. Therefore, choices A, C, and D are incorrect as they have different functions compared to the thyroid gland.

Correct Answer: A

Rationale: A convex lens is characterized by its ability to converge light rays. The convex lens is thicker in the middle and thinner at the edges, causing light rays passing through it to converge or come together at a focal point on the opposite side of the lens. This convergence of light rays is what distinguishes convex lenses. Choice B is incorrect as convex lenses do not diverge light rays. Choice C is incorrect as convex lenses do not focus sound waves but rather light waves. Choice D is incorrect as convex lenses can create both real and virtual images, not just virtual images.

Correct Answer: A

Rationale: The correct answer is Sodium. Sodium is found in water and is crucial for biological functions like nerve impulses and muscle contraction. It plays a key role in maintaining electrolyte balance and transmitting nerve impulses, affecting both muscles and nerves. Potassium (Choice B), although essential for nerve function and muscle control, is not typically found in water. Calcium (Choice C) is important for bone health and muscle function, but it is not the element found in water. Magnesium (Choice D) is also essential for various biological functions but is not the element commonly found in water.

Correct Answer: B

Rationale: Veins are the blood vessels that carry deoxygenated blood from the body back to the heart. Arteries transport oxygenated blood away from the heart. Capillaries are the smallest blood vessels where gas exchange occurs between blood and tissues. Venules are small veins that connect capillaries to larger veins, but they do not directly carry deoxygenated blood back to the heart.