Nokea
What type of reaction is represented by the following equation: Fe2O3 (s) + 3H2 (g) -> 2Fe (s) + 3H2O (g)?
- A. Combustion
- B. Decomposition
- C. Single displacement
- D. Redox reaction
Correct Answer: C
Rationale: The correct answer is C: Single displacement. This reaction is a single displacement reaction because the iron (Fe) in Fe2O3 is displaced by the hydrogen (H) in H2 to form Fe and H2O. In single displacement reactions, one element replaces another in a compound. Choice A, Combustion, involves a reaction with oxygen typically producing heat, light, and often a flame. Choice B, Decomposition, is when a compound breaks down into simpler substances. Choice D, Redox reaction, involves both reduction and oxidation reactions happening simultaneously, which is not the case in the provided equation.
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When ethanol (Câ‚‚Hâ‚…OH) reacts with sodium metal (Na), what is the product?
- A. Ethene (Câ‚‚Hâ‚„)
- B. Sodium ethoxide (Câ‚‚Hâ‚…ONa)
- C. Ethane (C₂H₆)
- D. Sodium acetate (CH₃COONa)
Correct Answer: B
Rationale: When ethanol (C₂H₅OH) reacts with sodium metal (Na), the product formed is Sodium ethoxide (C₂H₅ONa). This reaction is a classic example of a metal displacing hydrogen in an alcohol to form an alkoxide. In this specific case, sodium replaces the hydrogen in ethanol, resulting in the formation of sodium ethoxide. Choice A, Ethene (C₂H₄), is incorrect as it is a different compound formed from the dehydration of ethanol, not its reaction with sodium. Choice C, Ethane (C₂H₆), is incorrect as it is a saturated hydrocarbon, not the product of the reaction of ethanol with sodium metal. Choice D, Sodium acetate (CH₃COONa), is incorrect as it involves acetic acid, not ethanol, reacting with sodium to form the salt sodium acetate.
What causes lymphedema, a chronic condition, to occur?
- A. Inflammation of lymph nodes
- B. Blockage of lymph vessels
- C. Malfunction of the spleen
- D. Decrease in bone marrow production
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.
What type of muscle tissue is responsible for causing the hair follicles to stand on end when you get a goosebump?
- A. Skeletal muscle
- B. Smooth muscle
- C. Cardiac muscle
- D. None of the above
Correct Answer: B
Rationale: Smooth muscle is responsible for causing the hair follicles to stand on end when you get a goosebump. This type of muscle tissue is found in the skin attached to hair follicles and contracts in response to stimuli such as cold or fear, causing the hair to stand up. Skeletal muscle is responsible for voluntary movements, and cardiac muscle is found in the heart and is not directly involved in causing goosebumps. Therefore, choices A, C, and D are incorrect as they do not represent the specific type of muscle tissue responsible for this physiological response.
Which part of the brainstem is responsible for controlling vital functions such as heart rate, blood pressure, and breathing?
- A. Medulla oblongata
- B. Pons
- C. Midbrain
- D. Cerebellum
Correct Answer: A
Rationale: The medulla oblongata is the correct answer. It is responsible for controlling vital functions such as heart rate, blood pressure, and breathing. This part of the brainstem contains centers that regulate these essential autonomic functions to maintain homeostasis in the body. The pons and midbrain are also parts of the brainstem, but they are not primarily responsible for controlling these vital functions. The cerebellum, on the other hand, is involved in coordination and balance, not in regulating vital functions like heart rate, blood pressure, and breathing.
What is the main function of the urinary system?
- A. Transporting oxygen
- B. Fighting off infections
- C. Maintaining acid-base balance
- D. All of the above
Correct Answer: C
Rationale: The main function of the urinary system is to maintain the body's acid-base balance. This is achieved by regulating the levels of electrolytes and water in the body. The kidneys filter waste products from the blood to form urine, which helps to regulate the pH balance. Choice A, transporting oxygen, is primarily the function of the respiratory system. Choice B, fighting off infections, is a function of the immune system. Therefore, the correct answer is maintaining acid-base balance.