Nursing Elites

1. If oxygen is in a compound, what would its oxidation number be?

• A. 2
• B. -2
• C. 0
• D. -1

Correct answer: B

Rationale: Oxygen typically has an oxidation number of -2 in compounds because it tends to gain electrons. This is due to its high electronegativity, which leads to oxygen attracting electrons towards itself in a chemical bond. Choice A (2) is incorrect because oxygen doesn't have a +2 oxidation number in compounds. Choice C (0) is incorrect as oxygen rarely has an oxidation number of 0 in compounds. Choice D (-1) is incorrect as oxygen's oxidation number in compounds is typically -2, not -1.

2. Which is a triatomic allotrope of oxygen?

• A. Ozone
• B. Water
• C. Acidic oxide
• D. Carbon dioxide

Correct answer: A

Rationale: Ozone (O3) is a triatomic allotrope of oxygen. It differs from the common diatomic oxygen molecule (O2) by having three oxygen atoms bonded together. Ozone is known for its protective role in the Earth's atmosphere, absorbing most of the Sun's harmful ultraviolet radiation. Water (H2O) is a compound composed of two hydrogen atoms and one oxygen atom. Acidic oxide and carbon dioxide are not triatomic allotropes of oxygen. Carbon dioxide consists of one carbon atom and two oxygen atoms, while acidic oxides refer to compounds where oxygen is bonded with other elements to form oxides, and they are not allotropes of oxygen.

3. What is stoichiometry?

• A. The study of energy changes in chemical reactions
• B. The study of the mass relationships in chemical reactions
• C. The study of atomic structure
• D. The study of molecular geometry

Correct answer: B

Rationale: Stoichiometry is the branch of chemistry that deals with the quantitative relationships between reactants and products in chemical reactions. It focuses on the calculation of the amounts of substances consumed and produced in a reaction based on the balanced chemical equation. Choice A is incorrect because the study of energy changes in chemical reactions falls under thermodynamics. Choice C is incorrect as atomic structure is related to the arrangement of atoms within molecules. Choice D is incorrect as molecular geometry deals with the spatial arrangement of atoms within molecules.

4. What is a pentose sugar?

• A. A 6 carbon sugar
• B. A 4 carbon sugar
• C. A 5 carbon sugar
• D. A 7 carbon sugar

Correct answer: C

Rationale: A pentose is a 5-carbon sugar, as the prefix 'pent-' signifies five. Therefore, a pentose sugar consists of five carbon atoms. Choice A, 'A 6 carbon sugar,' is incorrect as a pentose sugar specifically has five carbons. Choice B, 'A 4 carbon sugar,' is incorrect as it describes a tetrose sugar, which has four carbons. Choice D, 'A 7 carbon sugar,' is incorrect as it does not correspond to the definition of a pentose sugar.

5. Which statement is true of a saturated solution?

• A. It has more solute than can dissolve in the solvent.
• B. It has less solute that can dissolve in the solvent.
• C. It has the maximum concentration of the solute dissolved in the solvent.
• D. It contains a precipitate that lowers the concentration of the solute in the solvent.

Correct answer: C

Rationale: A saturated solution contains the maximum concentration of solute that can be dissolved in a specific amount of solvent at a particular temperature. Once a solution is saturated, adding more solute will not increase its concentration since the excess solute will not dissolve and will instead form a precipitate, indicating that the solution is at its maximum capacity. Choices A, B, and D are incorrect because a saturated solution has reached its limit in dissolving solute, so it cannot contain more solute than it can dissolve (choice A), less solute than it can dissolve (choice B), or a precipitate that lowers the concentration of the solute in the solvent (choice D).

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