Nursing Elites

1. Which element is used in fire extinguishers to smother flames by displacing oxygen?

• A. Nitrogen
• B. Carbon dioxide
• C. Helium
• D. Argon

Correct answer: B

Rationale: Carbon dioxide is the correct answer. It is used in fire extinguishers because it displaces oxygen, which is necessary for combustion. When carbon dioxide is released onto a fire, it reduces the oxygen concentration around the flames, effectively smothering the fire. This disruption of oxygen availability interrupts the chemical reaction that sustains the fire. Nitrogen (Choice A), helium (Choice C), and argon (Choice D) are not typically used in fire extinguishers for smothering flames by displacing oxygen. Nitrogen is an inert gas that can displace oxygen but is not as effective as carbon dioxide in fire suppression.

2. Where is oxygen exchanged between blood and tissues?

• A. capillaries
• B. veins
• C. ventricles
• D. arteries

Correct answer: A

Rationale: Oxygen is exchanged between blood and tissues primarily at the capillaries. Capillaries are the smallest blood vessels where the exchange of oxygen, nutrients, and waste products occurs between the blood and the tissues. This exchange process is crucial for delivering oxygen to the body's cells and eliminating carbon dioxide waste. Veins carry blood back to the heart, arteries carry blood away from the heart, and ventricles are the lower chambers of the heart responsible for pumping blood. Therefore, capillaries are the correct answer for where oxygen is exchanged between blood and tissues.

3. 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.

4. Which type of isomerism arises due to differences in the arrangement of atoms around a double bond?

• A. Chain isomerism
• B. Functional group isomerism
• C. Cis-trans isomerism
• D. Stereoisomerism

Correct answer: C

Rationale: Cis-trans isomerism, also known as geometric isomerism, arises due to differences in the arrangement of atoms around a double bond. In cis isomers, similar groups are on the same side of the double bond, while in trans isomers, similar groups are on opposite sides of the double bond. This type of isomerism is a subset of stereoisomerism, which includes all isomers that have the same connectivity but differ in spatial arrangement. Chain isomerism involves differences in the carbon chain arrangement, functional group isomerism involves different functional groups, and stereoisomerism is a broader category that encompasses isomers with the same connectivity but different spatial arrangement.

5. What is the term for a solution that has exactly the same concentration of solute as another solution?

• A. Saturated solution
• B. Unsaturated solution
• C. Isotonic solution
• D. Concentrated solution

Correct answer: C

Rationale: An isotonic solution is a solution that has the same concentration of solute as another solution. When cells are placed in an isotonic solution, there is no net movement of water across the cell membrane, maintaining equilibrium. Choice A, a saturated solution, refers to a solution that contains the maximum amount of solute that can be dissolved at a given temperature. Choice B, an unsaturated solution, is a solution that contains less solute than a saturated solution under the same conditions. Choice D, a concentrated solution, is a solution with a high amount of solute compared to the solvent.

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