Nursing Elites

1. What happens during a physical change in matter?

• A. A new substance with different properties is formed
• B. The chemical composition of the substance changes
• C. The original substance can be recovered by physical means
• D. Energy is either released or absorbed

Correct answer: C

Rationale: During a physical change in matter, the original substance undergoes a change in its physical state or appearance without any change in its chemical composition. This means that the original substance can be recovered by physical means, such as melting, freezing, boiling, or condensing. No new substance is formed (option A), the chemical composition remains the same (option B), and energy changes can occur but are not a defining characteristic of a physical change (option D). The ability to recover the original substance by physical means distinguishes physical changes from chemical changes.

2. 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.

3. Which gland located in the neck is responsible for regulating metabolism, growth, and development?

• A. Parathyroid gland
• B. Thyroid gland
• C. Pituitary gland
• D. Thymus gland

Correct answer: B

Rationale: The thyroid gland, located in the neck, is responsible for regulating metabolism, growth, and development. It produces hormones such as thyroxine (T4) and triiodothyronine (T3) that play a crucial role in these functions. The parathyroid gland regulates calcium levels, the pituitary gland controls various hormonal functions, and the thymus gland is involved in immune system development. Therefore, choices A, C, and D are incorrect as they have different functions compared to the thyroid gland.

4. Which part of the brain is responsible for coordinating various sensory inputs, regulating sleep, and maintaining wakefulness?

• A. Cerebrum
• B. Hypothalamus
• C. Medulla oblongata
• D. Reticular formation

Correct answer: D

Rationale: The reticular formation is a network of neurons located in the brainstem that plays a crucial role in regulating sleep-wake cycles, coordinating various sensory inputs, and maintaining wakefulness. It acts as a filter for incoming sensory information and helps in directing attention to important stimuli. The other options, the cerebrum, hypothalamus, and medulla oblongata, are important structures in the brain but are not primarily responsible for the specific functions mentioned in the question. The cerebrum is mainly involved in higher brain functions such as thinking and voluntary movements. The hypothalamus is responsible for regulating body temperature, hunger, and thirst, among other functions. The medulla oblongata is essential for controlling vital autonomic functions like breathing and heart rate.

5. Which of the following is a common characteristic of alkynes?

• A. They have a triple bond between carbon atoms.
• B. They are saturated hydrocarbons.
• C. They contain only single bonds.
• D. They are aromatic compounds.

Correct answer: A

Rationale: The correct answer is A. Alkynes are hydrocarbons characterized by at least one triple bond between carbon atoms. This triple bond sets them apart from alkanes, which only have single bonds, and alkenes, which feature at least one double bond. The presence of a triple bond makes alkynes unsaturated hydrocarbons. Choice B is incorrect as alkynes are unsaturated hydrocarbons, not saturated. Choice C is incorrect because alkynes contain at least one triple bond, making them different from compounds with only single bonds. Choice D is incorrect because aromatic compounds have a distinct cyclic structure with resonance stabilization, a feature not shared by alkynes.

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