Nursing Elites

1. Which of the following best describes a chemical change?

• A. Melting ice to form water
• B. Dissolving sugar in water
• C. Burning wood to produce ash
• D. Crushing a can to reduce its size

Correct answer: c

Rationale: Chemical changes involve the formation of new substances with different chemical properties. Burning wood involves a chemical reaction where wood undergoes combustion, breaking down its chemical structure to produce new substances like ash and gases.

2. The constituents of an atomic nucleus consist of:

• A. Electrons and protons only
• B. Protons and neutrons only
• C. Electrons, protons, and neutrons
• D. None of the above

Correct answer: B

Rationale: The correct answer is B: "Protons and neutrons only." This is because the atomic nucleus is composed of protons, which carry a positive charge, and neutrons, which are neutral. Electrons are found outside the nucleus in electron shells. Protons and neutrons are collectively known as nucleons and are responsible for the mass of the atom. Electrons are much lighter and are involved in chemical reactions and bonding. Therefore, the constituents of an atomic nucleus are specifically protons and neutrons, making option B the correct choice.

3. What is the term for the small air sacs in the lungs where gas exchange (oxygen and carbon dioxide) takes place?

• A. Bronchi
• B. Alveoli
• C. Trachea
• D. Bronchioles

Correct answer: B

Rationale: The correct answer is B: Alveoli. Alveoli are the small air sacs in the lungs where gas exchange occurs. Oxygen from the air we breathe diffuses into the blood in the capillaries surrounding the alveoli, while carbon dioxide diffuses from the blood into the alveoli to be exhaled. Bronchi (A) are the large airways that branch off the trachea (C) and lead into the lungs. Bronchioles (D) are smaller airways that branch off the bronchi. Understanding the structure and function of the respiratory system is important for comprehending how oxygen is taken in and carbon dioxide is removed from the body.

4. A convex lens is characterized by its ability to:

• A. Converge light rays
• B. Diverge light rays
• C. Focus sound waves
• D. Create virtual images only

Correct answer: A

Rationale: The correct answer is A: 'Converge light rays.' A convex lens is thicker in the center and thinner at the edges, causing light rays passing through it to converge or come together at a focal point. This ability is what enables convex lenses to bend light rays inward, focusing them to produce clear images. Options B and C are incorrect because convex lenses do not diverge light rays or focus sound waves. Option D is also incorrect as convex lenses can create both real and virtual images based on the position of the object with respect to the lens. Therefore, the main characteristic of a convex lens is its ability to converge light rays to form focused images.

5. What property of a substance remains constant regardless of the amount of the substance present?

• A. Mass
• B. Weight
• C. Density
• D. Volume

Correct answer: c

Rationale: Density remains constant for a specific substance regardless of the quantity present. It's the mass per unit volume and remains the same for a substance.

6. Which of the following is an example of stabilizing selection?

• A. Selection that favors extreme traits in a population
• B. Selection that removes individuals with extreme traits
• C. Selection that maintains the current average trait in a population
• D. Selection that favors one specific trait over all others

Correct answer: C

Rationale: Rationale: - Stabilizing selection is a type of natural selection that favors the intermediate variants in a population, while selecting against the extreme traits. This results in the maintenance of the current average trait in the population. - Option A is incorrect because stabilizing selection does not favor extreme traits; instead, it favors the average trait. - Option B is incorrect because stabilizing selection does not remove individuals with extreme traits; it acts against extreme traits by favoring the intermediate variants. - Option D is incorrect because stabilizing selection does not favor one specific trait over all others; it favors the average trait by selecting against extreme traits.

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