Nursing Elites

1. In the reaction 2H2 + O2 → 2H2O, how many moles of oxygen are required to react completely with 4 moles of hydrogen?

• A. 1
• B. 2
• C. 3
• D. 4

Correct answer: B

Rationale: The balanced chemical equation indicates that 2 moles of H2 react with 1 mole of O2 to produce 2 moles of H2O. To determine how many moles of O2 are required to react with 4 moles of H2, you can use the mole ratio from the balanced equation: 2 moles of H2 react with 1 mole of O2. Therefore, to react completely with 4 moles of H2, you would need 2 moles of O2 (4 moles H2 ÷ 2 moles H2 per 1 mole O2). Hence, 2 moles of oxygen are required to react completely with 4 moles of hydrogen. Choices A, C, and D are incorrect because they do not reflect the correct stoichiometry as defined by the balanced chemical equation.

2. Which of the following is a characteristic of unsaturated fatty acids?

• A. They are solid at room temperature.
• B. They contain only single bonds.
• C. They have a higher melting point.
• D. They contain double or triple bonds.

Correct answer: D

Rationale: The correct answer is D. Unsaturated fatty acids are characterized by the presence of double or triple bonds in their carbon chain. These bonds introduce kinks in the chain, preventing tight packing, and resulting in a lower melting point compared to saturated fatty acids. Choice A is incorrect because unsaturated fatty acids are typically liquid at room temperature due to their kinked structure. Choice B is incorrect because unsaturated fatty acids contain double or triple bonds, not only single bonds. Choice C is incorrect as unsaturated fatty acids have a lower melting point compared to saturated fatty acids.

3. Which of the following represents different types of electromagnetic waves based on their wavelengths and frequencies?

• A. Visible light, X-rays, radio waves, gamma rays
• B. Sound waves, water waves, seismic waves, shock waves
• C. Longitudinal waves, transverse waves, mechanical waves, non-mechanical waves
• D. None of the above

Correct answer: A

Rationale: Electromagnetic waves are categorized based on their wavelengths and frequencies. Visible light, X-rays, radio waves, and gamma rays are all examples of electromagnetic waves with distinct wavelengths and frequencies. The correct answer choice, A, accurately represents different types of electromagnetic waves. Sound waves, water waves, seismic waves, and shock waves are mechanical waves that propagate through a medium via particle interactions, not electromagnetic waves. Longitudinal waves, transverse waves, mechanical waves, and non-mechanical waves are classifications based on the nature of the wave propagation and do not relate to the types of electromagnetic waves which are differentiated by their electromagnetic properties.

4. Which of the following is part of the cardiovascular system?

• A. Blood vessels
• B. Brain
• C. Kidneys
• D. Lungs

Correct answer: A

Rationale: Blood vessels are indeed part of the cardiovascular system. They are crucial components that facilitate blood circulation by carrying blood throughout the body. The cardiovascular system consists of the heart, blood vessels (arteries, veins, and capillaries), and blood. Blood vessels play a vital role in delivering oxygen and nutrients to tissues and removing waste products. The brain, kidneys, and lungs are not part of the cardiovascular system; instead, they belong to other body systems. The brain is part of the nervous system, kidneys are part of the urinary system, and lungs are part of the respiratory system. Therefore, the correct answer is blood vessels (Choice A). Choices B, C, and D are incorrect as they are not components of the cardiovascular system but belong to different body systems.

5. What is the difference between active and passive immunity?

• A. Active immunity is short-lived, while passive immunity is long-lasting.
• B. Active immunity involves the body's own immune response, while passive immunity provides immediate protection through antibodies from another source.
• C. Active immunity only protects against bacterial infections, while passive immunity works against both bacteria and viruses.
• D. Passive immunity requires repeated vaccinations, while active immunity is a one-time process.

Correct answer: B

Rationale: Active immunity involves the body's own immune response, where the individual's immune system produces antibodies in response to exposure to a pathogen or vaccine. This type of immunity is long-lasting because the immune system 'remembers' the pathogen and can mount a rapid response upon re-exposure. In contrast, passive immunity provides immediate protection through the transfer of pre-formed antibodies from another source, such as through maternal antibodies crossing the placenta or receiving antibodies through an injection. Passive immunity is short-lived because the transferred antibodies eventually degrade and are not produced by the recipient's immune system. Choice A is incorrect because active immunity is generally long-lasting, as it involves the production of antibodies by the individual's immune system. Choice C is incorrect as both active and passive immunity can work against various pathogens, not limited to bacteria or viruses. Choice D is incorrect as passive immunity does not require repeated vaccinations but provides temporary protection through the transfer of antibodies from an external source.

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