Nursing Elites

1. How many moles of oxygen are required to completely react with 5 moles of propane (C3H8) in the combustion reaction?

• A. 5 moles
• B. 10 moles
• C. 15 moles
• D. 20 moles

Correct answer: C

Rationale: In the balanced chemical equation for the combustion of propane (C3H8): C3H8 + 5O2 → 3CO2 + 4H2O, 1 mole of propane (C3H8) reacts with 5 moles of oxygen (O2). To determine the moles of oxygen required to react with 5 moles of propane, we use the molar ratio: 5 moles propane x 5 moles oxygen / 1 mole propane = 25 moles oxygen. However, since the question specifically asks for the moles of oxygen needed to react with 5 moles of propane, the correct answer is 15 moles of oxygen. Choice A, 5 moles, is incorrect because this is the amount of propane provided, not the oxygen required. Choice B, 10 moles, is incorrect as it does not correspond to the molar ratio in the balanced equation. Choice D, 20 moles, is incorrect as it is not in line with the stoichiometry of the reaction.

2. What is the primary function of the CRISPR-Cas9 system in gene editing?

• A. To amplify specific DNA sequences.
• B. To cut DNA at specific locations.
• C. To deliver genes into cells.
• D. To sequence entire genomes.

Correct answer: B

Rationale: The CRISPR-Cas9 system is a powerful tool used in gene editing to precisely target and cut DNA at specific locations within the genome. This system consists of a guide RNA that directs the Cas9 enzyme to the desired DNA sequence, where it creates a double-strand break. This break can then be repaired by the cell's natural DNA repair mechanisms, allowing for the introduction of specific genetic modifications. Options A, C, and D are incorrect as they do not accurately describe the primary function of the CRISPR-Cas9 system in gene editing. Amplifying DNA sequences, delivering genes into cells, and sequencing entire genomes are not the main functions of the CRISPR-Cas9 system, which is primarily focused on precise DNA cutting for targeted genetic modifications.

3. What is the primary cause of acne vulgaris, commonly known as acne?

• A. Dry skin
• B. Clogged pores and excess oil production
• C. Bacterial infection alone
• D. Vitamin deficiency

Correct answer: B

Rationale: The primary cause of acne vulgaris is clogged pores and excess oil production. Acne develops when hair follicles become clogged with oil and dead skin cells, creating an environment for bacteria to thrive, leading to inflammation and acne breakouts. While dry skin, bacterial infection alone, and vitamin deficiency can contribute to acne, they are not the main underlying cause. Therefore, the correct answer is clogged pores and excess oil production, as they form the basis for the development of acne vulgaris.

4. Which valves are part of the heart?

• A. Tricuspid, mitral, pulmonary, aortic
• B. Aortic, pulmonary, mitral, tricuspid
• C. Aortic, pulmonary, Erb's point, tricuspid
• D. Aortic, pulmonic, Erb's point, tricuspid

Correct answer: B

Rationale: The correct valves of the heart are the aortic, pulmonic, tricuspid, and mitral (bicuspid) valves. Choice B correctly lists the aortic, pulmonary, mitral, and tricuspid valves. Erb's point is not a valve but rather an auscultation point on the chest, making choices C and D incorrect.

5. What phenomenon explains the formation of rainbows in the sky?

• A. Diffraction
• B. Interference
• C. Refraction and dispersion of sunlight by water droplets
• D. Reflection from clouds

Correct answer: C

Rationale: Rainbows are formed due to the refraction and dispersion of sunlight by water droplets in the atmosphere. When sunlight enters a water droplet, it is refracted, then internally reflected, and finally refracted again as it exits the droplet. This dispersion of light into its component colors creates the beautiful rainbow we see in the sky. Choice A, diffraction, involves bending of light around obstacles or through narrow openings, not the splitting of light into colors as seen in rainbows. Choice B, interference, refers to the phenomenon where two or more light waves overlap and interact, producing a pattern of light and dark bands, which is not the case with rainbows. Choice D, reflection from clouds, does not accurately describe the process involved in the formation of rainbows through refraction and dispersion of light by water droplets.

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