Nursing Elites

1. Which of the following is a colligative property of a solution?

• A. Freezing point depression
• B. Viscosity
• C. Surface tension
• D. Boiling point elevation

Correct answer: A

Rationale: A colligative property is a property that depends on the number of solute particles in a solution, not on the identity of the solute particles. Freezing point depression is one such property, where adding a solute to a solvent lowers the freezing point of the solution compared to the pure solvent. This phenomenon occurs because the presence of solute particles disrupts the formation of the regular crystal lattice structure, requiring a lower temperature for solidification to occur. Choices B, C, and D are not colligative properties. Viscosity and surface tension are not dependent on the number of solute particles but on intermolecular forces and molecular interactions. Boiling point elevation is another colligative property, but in this case, the question asked for a colligative property of a solution, making freezing point depression the correct answer.

2. What type of chemical reaction is represented by AB → A + B?

• A. Synthesis
• B. Decomposition
• C. Single replacement
• D. Double replacement

Correct answer: B

Rationale: The chemical equation AB → A + B represents a decomposition reaction. In a decomposition reaction, a single compound breaks down into two or more simpler substances. In this specific reaction, compound AB is decomposed into its elements, A and B, making it a decomposition reaction. Choice A, Synthesis, involves the combination of two or more substances to form a more complex product, which is not the case here. Choices C and D, Single replacement and Double replacement, involve the exchange of ions between compounds or elements, which is not happening in the given reaction.

3. Which one does not name a polar molecule?

• A. NH₃
• B. Hâ‚‚S
• C. SOâ‚‚
• D. COâ‚‚

Correct answer: A

Rationale: The correct answer is NH₃. The molecule NH₃ does not represent a polar molecule because nitrogen and hydrogen in this molecule have a small difference in electronegativity that does not result in a significant polar covalent bond. In contrast, molecules H₂S, SO₂, and CO₂ have polar covalent bonds due to larger electronegativity differences, making them polar molecules. Therefore, options B, C, and D are polar molecules, unlike option A.

4. Which of the following is the weakest intermolecular force?

• A. Dipole interactions
• B. Hydrogen bonding
• C. Van der Waals forces
• D. Dispersion forces

Correct answer: D

Rationale: Dispersion forces, also known as London dispersion forces, are the weakest intermolecular forces. They are temporary attractive forces that occur due to momentary shifts in electron distribution within molecules. While dipole interactions, hydrogen bonding, and Van der Waals forces are stronger intermolecular forces, dispersion forces are the weakest because they arise from short-lived fluctuations in electron density. Dipole interactions involve permanent dipoles in molecules, making them stronger than dispersion forces. Hydrogen bonding is stronger than dipole interactions and involves hydrogen atoms bonded to highly electronegative atoms. Van der Waals forces encompass dipole-dipole interactions and dispersion forces, making them stronger than dispersion forces alone.

5. What is an alloy in which another metal is dissolved in mercury (Hg) called?

• A. Electrum
• B. Amalgam
• C. Solder
• D. Bronze

Correct answer: B

Rationale: An amalgam is a type of alloy where another metal is dissolved in mercury (Hg). This process forms a unique mixture that has various applications in dentistry, chemistry, and other fields. Electrum is a natural alloy of gold and silver, solder is a metal alloy used to join other metals together, and bronze is a copper-tin alloy. Therefore, the correct answer is B - Amalgam.

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