A flask that weighs 345.8 g is filled with 225 mL of carbon tetrachloride. The weight of the flask and carbon tetrachloride is found to be 703.55 g. From this information, calculate the density of carbon tetrachloride.
- A. 1.59 g/mL
- B. 2.76 g/mL
- C. 1.4 g/mL
- D. None are correct.
Correct Answer: A
Rationale: To find the density of carbon tetrachloride, we need to use the formula Density = Mass / Volume. The mass of carbon tetrachloride can be calculated by subtracting the weight of the empty flask from the weight of the flask filled with carbon tetrachloride: Mass of carbon tetrachloride = 703.55 g - 345.8 g = 357.75 g. Now, we can calculate the density: Density = Mass / Volume = 357.75 g / 225 mL = 1.59 g/mL. Therefore, the correct answer is A, 1.59 g/mL.
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- C. DNA
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Correct Answer: B
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What is a combustion reaction?
- A. It absorbs heat.
- B. It involves the replacement of one element by another.
- C. It involves the sharing of electrons.
- D. It is a reaction that involves oxygen.
Correct Answer: D
Rationale: A combustion reaction is a chemical process that involves a substance reacting with oxygen to produce heat and light. The key component in a combustion reaction is oxygen, making choice D the correct answer. Combustion reactions are typically exothermic, releasing energy in the form of heat and light, making choice A incorrect. Choices B and C describe different types of chemical reactions, not combustion reactions. Therefore, the correct answer is D.
What is the term for the number of protons in an atom?
- A. atomic identity
- B. atomic mass
- C. atomic weight
- D. atomic number
Correct Answer: D
Rationale: The term for the number of protons in an atom is the atomic number. The atomic number is a fundamental property of an element, representing the number of protons in an atom's nucleus. It serves as the unique identity of an element and determines its position on the periodic table and its chemical behavior. Atomic mass refers to the average mass of an atom, including protons, neutrons, and electrons, while atomic weight is the average weight of an element considering the abundance of its isotopes. 'Atomic identity' is not a standard term in chemistry to describe the number of protons in an atom, making option D, 'atomic number,' the correct answer.
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- A. The measure of concentration of H₃O⺠ions
- B. The measure of concentration of hydrogen ions
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- D. None of the above
Correct Answer: A
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Which subatomic particle can always be used to identify an atom?
- A. Protons
- B. Neutrons
- C. Electrons
- D. None of the above
Correct Answer: A
Rationale: The correct answer is A: Protons. Protons are positively charged subatomic particles found in the nucleus of an atom. The number of protons in an atom's nucleus determines the element's identity. While neutrons and electrons are also essential components of an atom, it is the number of protons that uniquely identifies the element. Therefore, protons can always be used to identify an atom.
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