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What is the density of carbon tetrachloride if a flask weighing 345.8 g is filled with 225 mL of the liquid, and the total weight of the flask and liquid is 703.55 g?
- A. 1.59 g/mL
- B. 2.76 g/mL
- C. 1.4 g/mL
- D. None of the above
Correct Answer: A
Rationale: To find the density of carbon tetrachloride, we first need to determine the weight of the liquid only. The weight of the liquid can be calculated by subtracting the weight of the empty flask from the total weight of the flask and liquid: 703.55 g - 345.8 g = 357.75 g. Now, using the volume of the liquid (225 mL) and its weight (357.75 g), we can calculate the density: Density = Mass/Volume = 357.75 g / 225 mL ĉ� 1.59 g/mL. Therefore, the correct answer is A, 1.59 g/mL.
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What can be predicted using the periodic table?
- A. The properties of each of the elements
- B. The charge of polyatomic ions
- C. The number of isotopes in each element
- D. The potential for discovery of new elements
Correct Answer: A
Rationale: The periodic table serves as a fundamental tool in chemistry, organizing elements based on their atomic number, electron configuration, and recurring chemical properties. Through the arrangement of elements, one can predict various properties of each element. Periodic trends such as atomic radius, electronegativity, and ionization energy allow for the anticipation of element characteristics like reactivity, boiling point, and other physical and chemical properties. Hence, the correct answer is A: The properties of each of the elements can be successfully predicted using the periodic table.
What is 119 K in degrees Celsius?
- A. 32C
- B. -154C
- C. 154C
- D. -32C
Correct Answer: B
Rationale: To convert from Kelvin to Celsius, you subtract 273.15 from the temperature in Kelvin. Therefore, 119 K - 273.15 = -154C. Hence, 119 K is equivalent to -154C. The correct answer is -154C, as it results from the conversion formula from Kelvin to Celsius.
What is the term for the reactant that is entirely consumed by the reaction?
- A. limiting reactant
- B. reducing agent
- C. reaction intermediate
- D. reagent
Correct Answer: A
Rationale: The correct answer is A, limiting reactant. In a chemical reaction, the limiting reactant is the substance that is entirely consumed when the reaction reaches completion. It determines the maximum amount of product that can be formed. The reducing agent (choice B) is a substance that donates electrons to another chemical species, the reaction intermediate (choice C) is a molecule formed and consumed in different steps of the reaction, and a reagent (choice D) is a general term for any substance participating in a chemical reaction.
What distinguishes the 20 common amino acids from each other?
- A. Color
- B. Size
- C. R-group
- D. None of the above
Correct Answer: C
Rationale: The correct answer is C: R-group. The 20 common amino acids share a common backbone structure, but what differentiates them from each other is the side chain or R-group attached to this backbone. The R-group varies in composition and properties among the different amino acids, influencing their overall characteristics and functions. Options A and B are not the primary distinguishing factors among amino acids. Option D is incorrect as the R-group is the key feature that sets apart the 20 common amino acids, contributing to their individual identities and roles in biological processes.
In an experiment, a student tests three unknown fluids with the following measurements: Fluid A: m=2060g, V=2000mL, Fluid B: m=672g, V=850mL, and Fluid C: m=990g, V=1100mL. Arrange the liquids in the correct order of how they would separate in a beaker from bottom to top.
- A. A, B, C
- B. B, C, A
- C. C, A, B
- D. B, A, C
Correct Answer: B
Rationale: To determine the order in which the liquids will separate in a beaker, we must consider their densities, calculated using the formula Density = Mass (m) / Volume (V). The liquid with the higher density will settle at the bottom, while the liquid with the lower density will rise to the top. For the given fluids, Fluid A has a density of 1.03 g/mL (2060 g / 2000 mL), Fluid B has a density of approximately 0.79 g/mL (672 g / 850 mL), and Fluid C has a density of approximately 0.90 g/mL (990 g / 1100 mL). Based on these calculations, the correct order of the fluids from bottom to top, according to increasing density, is Fluid B, Fluid C, and Fluid A.