Nursing Elites

1. What is the oxidation state of carbon in CH4?

• A. +1
• B. -1
• C. +2
• D. -4

Correct answer: D

Rationale: In CH4 (methane), carbon is bonded to four hydrogen atoms. Hydrogen has an oxidation state of +1. Since the overall charge of CH4 is 0, the oxidation state of carbon must be -4 to balance the charges. Each hydrogen contributes an oxidation state of +1, resulting in a total of +4 from hydrogen atoms. To achieve a total oxidation state of 0 for the molecule, carbon must have an oxidation state of -4 to offset the contribution from hydrogen. Therefore, the correct answer is -4. Choices A, B, and C are incorrect: +1 is the oxidation state of hydrogen, -1 is not the oxidation state of carbon in methane, and +2 is not the correct oxidation state of carbon in CH4.

2. Which of the following statements correctly describes the function of a physiological structure?

• A. The trachea connects the throat and the stomach.
• B. The esophagus joins the larynx with the lungs.
• C. The diaphragm controls the height of the thoracic cavity.
• D. The epiglottis covers the trachea during swallowing.

Correct answer: D

Rationale: The epiglottis is a flap of tissue that covers the trachea during swallowing to prevent food and liquids from entering the airway. This action helps direct food into the esophagus, ensuring proper passage into the digestive system and avoiding potential choking or aspiration into the lungs. Choices A, B, and C are incorrect because the trachea connects the larynx to the bronchi, the esophagus connects the throat to the stomach, and the diaphragm is a muscle that plays a vital role in breathing by separating the thoracic and abdominal cavities, aiding in respiration.

3. How does the human eye focus light?

• A. Cornea
• B. Iris
• C. Lens
• D. Retina

Correct answer: C

Rationale: The human eye focuses light by adjusting the shape of its lens. The lens changes shape to allow the eye to focus on objects at different distances, a process known as accommodation. The cornea is the transparent outer covering of the eye that helps to focus light but does not change shape like the lens. The iris controls the size of the pupil to regulate the amount of light entering the eye. The retina is the light-sensitive layer at the back of the eye that receives and processes images but does not adjust the focus of light.

4. What is the basic structural and functional unit of the kidney?

• A. Neuron
• B. Nephron
• C. Glomerulus
• D. Axon

Correct answer: B

Rationale: The correct answer is B, Nephron. The nephron is indeed the basic structural and functional unit of the kidney. It is responsible for filtering blood, regulating electrolytes, maintaining fluid balance, and removing waste products. Choice A, Neuron, is incorrect as neurons are nerve cells, not specific to kidney function. Choice C, Glomerulus, is a component of the nephron but not the entire functional unit. Choice D, Axon, is a part of nerve cells and is not related to kidney structure or function.

5. What is the primary function of the epiglottis in the respiratory system?

• A. Filtration of air
• B. Production of mucus
• C. Prevention of food entering the trachea
• D. Oxygen exchange in the alveoli

Correct answer: C

Rationale: The primary function of the epiglottis in the respiratory system is to prevent food from entering the trachea. During swallowing, the epiglottis covers the opening of the trachea, guiding food down the esophagus to the stomach and preventing it from entering the airway. This mechanism safeguards the respiratory system from foreign objects, ensuring proper air passage and avoiding potential choking hazards. Choices A, B, and D are incorrect: A) Filtration of air is mainly performed by the nasal hairs and the mucous membranes of the respiratory tract. B) Production of mucus is primarily carried out by the mucous glands in the respiratory system to trap particles and humidify the air. D) Oxygen exchange in the alveoli occurs in the lungs and is related to the process of respiration, not the function of the epiglottis.

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