Nursing Elites

1. What is the coefficient of oxygen in the balanced chemical equation for the combustion of methane (CH₄)?

• A. 1
• B. 2
• C. 3
• D. 4

Correct answer: B

Rationale: In the balanced chemical equation for the combustion of methane, CH₄ + 2O₂ → CO₂ + 2H₂O, the coefficient of oxygen (O₂) is 2. This indicates that two molecules of oxygen are required to react with one molecule of methane to produce carbon dioxide and water, ensuring the equation is balanced. Choice A is incorrect because the coefficient of oxygen is not 1 but 2. Choices C and D are incorrect as they do not represent the correct coefficient of oxygen in the balanced equation. Understanding the coefficients in a balanced chemical equation is crucial for accurately representing the stoichiometry of the reaction.

2. Which of the following is the cytoplasmic organelle that contains fluid-filled tubules for carrying and transporting substances?

• A. Endoplasmic reticulum
• B. Golgi apparatus
• C. Mitochondria
• D. Nucleus

Correct answer: A

Rationale: The endoplasmic reticulum is the correct answer. It is the cytoplasmic organelle that contains fluid-filled tubules responsible for carrying and transporting substances within the cell. The endoplasmic reticulum plays a crucial role in protein synthesis, lipid metabolism, and detoxification processes. The Golgi apparatus, although important in modifying, sorting, and packaging proteins for secretion or for use within the cell, does not primarily contain fluid-filled tubules for carrying and transporting substances. Mitochondria are responsible for generating ATP through cellular respiration, not for carrying and transporting substances. The nucleus contains the cell's genetic material and is involved in regulating cellular activities but does not contain fluid-filled tubules for transportation.

3. In a single displacement reaction, one element takes the place of another element in a compound. Which of the following is an example?

• A. 2H2 + O2 -> 2H2O
• B. Zn + 2HCl -> ZnCl2 + H2
• C. CaCO3 -> CaO + CO2
• D. CH4 + 2O2 -> CO2 + 2H2O

Correct answer: B

Rationale: Option B demonstrates a single displacement reaction where zinc (Zn) displaces hydrogen (H) in hydrochloric acid (HCl) to produce zinc chloride (ZnCl2) and hydrogen gas (H2). This reaction exemplifies the concept of one element (Zn) replacing another element (H) in a compound (HCl), which is characteristic of single displacement reactions. Choices A, C, and D do not involve a single element displacing another in a compound, making them incorrect. In choice A, hydrogen and oxygen combine to form water, which is not a single displacement reaction. In choice C, calcium carbonate decomposes into calcium oxide and carbon dioxide, not involving displacement of elements. In choice D, methane reacts with oxygen to form carbon dioxide and water, which is a combustion reaction, not a single displacement reaction.

4. Which structure in the ear is responsible for maintaining balance?

• A. Cochlea
• B. Semicircular canals
• C. Eardrum
• D. Auditory nerve

Correct answer: B

Rationale: The correct answer is the semicircular canals. These structures in the inner ear are responsible for maintaining balance and equilibrium by detecting rotational movements of the head. The cochlea is responsible for hearing as it contains the sensory cells for detecting sound vibrations, the eardrum is a membrane that transmits sound waves to the middle ear, and the auditory nerve carries sound signals from the cochlea to the brain for processing. Therefore, choices A, C, and D are incorrect as they are not primarily associated with maintaining balance.

5. What type of lens is thinner at the center than at the edges and causes light rays to diverge?

• A. Convex lens
• B. Concave lens
• C. Diverging lens
• D. Plano-convex lens

Correct answer: B

Rationale: A concave lens is thinner at the center than at the edges, causing light rays to diverge when passing through it. This type of lens is also known as a diverging lens because it causes light rays to spread out. Concave lenses are used in various optical devices to correct vision problems and in scientific instruments to diverge light rays for specific purposes. The other choices are incorrect. A convex lens is thicker at the center and converges light rays, while a plano-convex lens has one flat surface and one convex surface, converging light. Diverging lens is a general term that can refer to concave or plano-concave lenses, but in this context, the specific type being referred to is a concave lens.

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