Nursing Elites

1. The chemical equation below is unbalanced. When it is properly balanced, how many molecules of carbon dioxide (CO2) are produced for each molecule of propane (C3H8) in the reaction? 3C3H8 + 5O2 → 3CO2 + 4H2O

• A. One Half.
• B. Two.
• C. Three.
• D. Five.

Correct answer: B

Rationale: The balanced chemical equation for the combustion of propane is: 3C3H8 + 5O2 → 3CO2 + 4H2O. This equation shows that for every 3 molecules of propane (C3H8) consumed, 3 molecules of carbon dioxide (CO2) are produced. Therefore, when properly balanced, 3CO2 are produced for each molecule of propane used. Thus, the correct answer is B: Two. Choices A, C, and D are incorrect because they do not reflect the correct stoichiometry as determined by the balanced equation.

2. What is the atomic number of an atom?

• A. The number of protons in an atom
• B. The number of neutrons in an atom
• C. The number of electrons in an atom
• D. The sum of protons and neutrons

Correct answer: A

Rationale: The correct answer is A: The atomic number of an atom is the number of protons in its nucleus. This number uniquely identifies the element, as each element has a distinct number of protons. Neutrons and electrons play roles in the atom's structure and stability, but the atomic number specifically refers to the number of protons. Choice B (The number of neutrons in an atom) is incorrect because the atomic number does not include neutrons; it only represents the number of protons. Choice C (The number of electrons in an atom) is incorrect because the atomic number is not related to the number of electrons, which can vary in different atomic configurations. Choice D (The sum of protons and neutrons) is incorrect because it refers to the mass number of an atom, which is the total number of protons and neutrons in the nucleus, not just the protons.

3. What is the role of the large intestine in the digestive system?

• A. To break down proteins
• B. To absorb water and form feces
• C. To digest fats
• D. To neutralize stomach acid

Correct answer: B

Rationale: The correct answer is B. The large intestine plays a crucial role in absorbing water from indigestible food matter and forming feces for elimination. Choice A is incorrect because the breakdown of proteins primarily occurs in the stomach and small intestine. Choice C is incorrect as the digestion of fats primarily occurs in the small intestine. Choice D is incorrect as neutralizing stomach acid is mainly the function of the stomach lining and not the large intestine.

4. What is the name of the cartilage flap that covers the trachea during swallowing, preventing food from entering the airway?

• A. Epiglottis
• B. Glottis
• C. Larynx
• D. Pharynx

Correct answer: A

Rationale: The correct answer is A: Epiglottis. The epiglottis is a cartilage flap located at the base of the tongue that covers the trachea during swallowing. Its primary function is to prevent food and liquids from entering the airway and instead directs them towards the esophagus. The glottis (choice B) refers to the space between the vocal cords in the larynx. The larynx (choice C) is the voice box containing the vocal cords responsible for phonation. The pharynx (choice D) is the throat region connecting the mouth and the esophagus, playing a role in both digestion and respiration.

5. Which of the following units is used to express concentration as a mass of solute per unit volume of solution?

• A. Molality (m)
• B. Molarity (M)
• C. Weight percent (%)
• D. Parts per million (ppm)

Correct answer: A

Rationale: Molality (m) is the unit used to express concentration as a mass of solute per unit volume of solution. It is calculated by dividing the mass of solute in grams by the mass of the solvent in kilograms. Molality is preferred over molarity when there are large temperature variations as it is temperature-independent, making it a more accurate measure of concentration. Molarity (B) is the unit used to express concentration as moles of solute per liter of solution, weight percent (C) is the mass of solute per 100 parts of the total mass of the solution, and parts per million (D) is used to express very small concentrations where 1 ppm is equivalent to 1 mg of solute per liter of solution.

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