What is the name of the phase change from liquid to gas?
- A. Condensation
- B. Sublimation
- C. Evaporation
- D. Melting
Correct Answer: C
Rationale: The correct answer is 'Evaporation.' This phase change occurs when a liquid turns into a gas. During evaporation, molecules gain enough energy to break free from the liquid phase and enter the gas phase, without the need for the liquid to reach its boiling point. Choice A, 'Condensation,' is the opposite phase change where gas turns into a liquid. Choice B, 'Sublimation,' is the phase change from solid directly to gas, skipping the liquid phase. Choice D, 'Melting,' is the phase change from solid to liquid.
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Which of the following elements is the most electronegative?
- A. Oxygen
- B. Fluorine
- C. Nitrogen
- D. Sodium
Correct Answer: B
Rationale: Fluorine is the most electronegative element on the periodic table. It has the highest electronegativity value, indicating its strong ability to attract electrons in a chemical bond. This property makes it highly reactive, explaining why it is the correct answer in this question. Oxygen and Nitrogen are also electronegative elements, but they are not as electronegative as Fluorine. Sodium, on the other hand, is not electronegative; it is an electropositive element.
What is the name of the bond formed when two atoms share electrons?
- A. Covalent bond
- B. Ionic bond
- C. Metallic bond
- D. Hydrogen bond
Correct Answer: A
Rationale: A covalent bond is formed when two atoms share electrons, creating a stable electron configuration. This sharing allows both atoms to achieve a full outer shell of electrons, leading to a stable molecule. In contrast, an ionic bond involves the transfer of electrons from one atom to another, resulting in the formation of ions with opposite charges. Metallic bonds are formed between metal atoms and involve a 'sea of electrons' that are delocalized and free to move. Hydrogen bonds are a type of intermolecular force, not a true chemical bond, and occur between a hydrogen atom and a highly electronegative atom like oxygen or nitrogen.
What is the name of the process by which a gas turns into a liquid?
- A. Sublimation
- B. Condensation
- C. Evaporation
- D. Deposition
Correct Answer: B
Rationale: The correct answer is B: Condensation. Condensation is the process where gas transforms into a liquid. When gas cools down, it loses energy and its particles come closer, leading to the formation of liquid droplets. Sublimation is the direct transition from solid to gas without passing through the liquid state. Evaporation is the process of liquid turning into a gas, and deposition is the transition of gas directly into a solid. Therefore, choices A, C, and D are incorrect as they describe different phase transitions.
Which of the following elements is a noble gas?
- A. Hydrogen
- B. Fluorine
- C. Argon
- D. Nitrogen
Correct Answer: C
Rationale: The correct answer is C: Argon. Argon is a noble gas, part of Group 18 in the periodic table. Noble gases are colorless, odorless, and typically non-reactive under normal conditions. Other elements in this group include helium, neon, krypton, xenon, and radon. Argon finds wide applications in welding, lighting, and scientific research. Choices A, B, and D are not noble gases. Hydrogen is a non-metal, Fluorine is a halogen, and Nitrogen is a diatomic non-metal gas.
What is another name for aqueous HI?
- A. hydroiodic acid
- B. hydrogen monoiodide
- C. hydrogen iodide
- D. hydriodic acid
Correct Answer: D
Rationale: The correct name for aqueous HI is 'hydriodic acid.' When hydrogen iodide (HI) dissolves in water, it forms hydriodic acid. Therefore, 'hydriodic acid' is the appropriate term for aqueous HI. Choice A, 'hydroiodic acid,' is incorrect as it does not reflect the nature of the compound in the aqueous state. Choice B, 'hydrogen monoiodide,' is not a widely recognized term for this compound. Choice C, 'hydrogen iodide,' is the name for HI in the gaseous state, not when it's dissolved in water.