Nursing Elites

1. How many moles of water are produced when 0.5 moles of methane (CH4) react with excess oxygen?

• A. 0.5 moles
• B. 1 mole
• C. 2 moles
• D. 3 moles

Correct answer: B

Rationale: The balanced chemical equation for the combustion of methane is: CH4 + 2O2 -> CO2 + 2H2O. This equation shows that 1 mole of methane produces 2 moles of water. Therefore, when 0.5 moles of methane react, they will produce 1 mole of water. The ratio of water to methane is 2:1, meaning that for every mole of methane that reacts, it produces 2 moles of water. Since only 0.5 moles of methane are reacting, the amount of water produced will be half of what would be produced if 1 mole of methane reacted, resulting in 1 mole of water being produced. Choice A is incorrect because it does not consider the stoichiometry of the reaction. Choices C and D are incorrect as they do not align with the balanced chemical equation and the stoichiometric ratios involved in the reaction.

2. How does sunscreen protect the skin from harmful ultraviolet (UV) rays?

• A. By reflecting UV rays away from the skin
• B. By absorbing UV rays and converting them to heat
• C. By blocking UV rays completely
• D. By stimulating melanin production

Correct answer: B

Rationale: Sunscreen works by absorbing UV rays and converting them to heat. This mechanism helps to prevent the UV rays from penetrating the skin and causing damage such as sunburn, premature aging, and skin cancer. Reflecting UV rays away from the skin (option A) is not the primary function of sunscreen. While sunscreen does block UV rays, it does not do so completely (option C) as some UV rays may still penetrate the skin. Sunscreen does not stimulate melanin production (option D) as a means of protecting the skin from UV rays.

3. Which of the following is an example of adaptive immunity?

• A. Inflammation
• B. Fever
• C. Antibodies
• D. Phagocytosis

Correct answer: C

Rationale: Antibodies are produced by the adaptive immune system in response to specific antigens. They play a crucial role in targeting and neutralizing pathogens, providing long-lasting immunity against future infections. In contrast, options A (inflammation), B (fever), and D (phagocytosis) are examples of innate immunity, the body's immediate, non-specific defense mechanisms. Inflammation is a response to tissue damage, fever is a systemic response to infection, and phagocytosis is a process where cells engulf and digest pathogens, all part of the innate immune response.

4. Which of the following has a smaller genetic scale than a chromosome?

• A. Genome
• B. Gene
• C. DNA
• D. All of the above

Correct answer: B

Rationale: The correct answer is 'B: Gene.' A gene is a segment of DNA and is smaller in scale than a chromosome. Genes are the fundamental units of heredity, containing the instructions for building and maintaining an organism. While a chromosome is a larger structure that carries many genes, each gene is a specific segment of DNA responsible for encoding a particular protein or RNA molecule. Choices A, C, and D are incorrect. The 'Genome' (Choice A) refers to the complete set of an organism's genetic material, including all of its genes, while 'DNA' (Choice C) is the molecule that carries the genetic instructions. 'All of the above' (Choice D) is incorrect because not all options have a smaller genetic scale than a chromosome.

5. What is the primary function of the strong nuclear force?

• A. Binding electrons in atomic orbitals
• B. Binding protons and neutrons within the nucleus
• C. Mediating the attractive force between opposite charges
• D. Mediating the repulsive force between like charges

Correct answer: B

Rationale: The strong nuclear force primarily functions to bind protons and neutrons within the nucleus. It is responsible for overcoming the electrostatic repulsion between positively charged protons, holding the nucleus together. Choices A, C, and D are incorrect because the strong nuclear force specifically acts on nucleons (protons and neutrons) within the nucleus, not on electrons in atomic orbitals or charges outside the nucleus.

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