Correct Answer: A

Rationale: The balanced chemical equation shows that 4 moles of aluminum react with 3 moles of oxygen to produce 2 moles of aluminum oxide. Therefore, the mole ratio of aluminum to oxygen is 4:3. Choice B (2:3) is incorrect because it does not reflect the correct ratio based on the balanced equation. Choice C (3:2) and Choice D (3:4) are also incorrect as they do not represent the correct mole ratio of aluminum to oxygen according to the balanced chemical equation.

Correct Answer: C

Rationale: The small intestine is the primary site of nutrient absorption in the digestive system. It is where the majority of digestion and absorption of nutrients such as carbohydrates, proteins, and fats occurs. The inner lining of the small intestine is covered in tiny finger-like projections called villi, which increase the surface area available for absorption. Nutrients are absorbed through the walls of the small intestine and into the bloodstream to be transported to cells throughout the body. The stomach's main role is to break down food through the action of stomach acids and enzymes but does not absorb nutrients. The large intestine primarily absorbs water and electrolytes from the remaining indigestible food matter, and the esophagus is a muscular tube that transports food from the mouth to the stomach, without being involved in nutrient absorption.

Correct Answer: B

Rationale: Friction is a force that opposes motion when two surfaces are in contact. It acts in the opposite direction to the direction of motion, causing objects to slow down or come to a stop. Therefore, friction decreases speed rather than increasing it. Choice A is incorrect as friction does not increase speed but rather hinders it. Choice C is incorrect because friction does have an impact on speed by slowing down objects. Choice D is incorrect as friction's effect is not making objects float but rather causing resistance to motion.

Correct Answer: B

Rationale: The autonomic nervous system is the correct answer. It is responsible for controlling involuntary functions such as heart rate, digestion, respiratory rate, and other automatic processes in the body. The somatic nervous system controls voluntary movements, making choice A incorrect. The peripheral nervous system consists of nerves outside the brain and spinal cord, which is not directly responsible for these involuntary functions, making choice C incorrect. The central nervous system includes the brain and spinal cord, but it is not primarily responsible for regulating involuntary functions, making choice D incorrect.

Correct Answer: D

Rationale: Adipose tissue serves multiple functions in the body, including insulation to regulate body temperature, energy storage in the form of triglycerides, and hormone production such as leptin and adiponectin. Adipose tissue does not directly participate in muscle movement. Muscle movement is primarily carried out by skeletal muscle tissue, which is responsible for voluntary movements and locomotion. Therefore, the correct answer is D, as adipose tissue is not involved in muscle movement.