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A scientist obtains the number 0.045006700 on a calculator. If this number
actually has four significant figures, how should it be written?
- A. 0.4567
- B. 0.4501
- C. 0.045
- D. 0.045
Correct Answer: C
Rationale: The correct answer is C: 0.045. When dealing with significant figures, trailing zeros after the decimal point are considered significant. In this case, the number 0.045006700 should be rounded to 0.045 since it has four significant figures. Choice A has too many significant figures, B rounds incorrectly, and D removes significant figures after the decimal point. Thus, C is the correct choice.
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Convert 0494 to L. (54 cm = 1 in., 1 L = 1 )
- A. 1.40 101 L
- B. 1.40 L
- C. 1.51 10 3 L
- D. 1.74 10 3 L
Correct Answer: A
Rationale: To convert 0494 to L, we first convert it to inches: 494 cm ÷ 54 cm/in = 9.148 in. Then, we convert inches to L: 9.148 in × 1 L/54 in = 0.169 L. The correct answer is A: 1.40 101 L, which is the correct conversion of 0.169 L to scientific notation. Choices B, C, and D are incorrect due to incorrect conversions or not being in scientific notation.
Alpha particles beamed at thin metal foil may
- A. pass directly through without changing direction
- B. be slightly diverted by attraction to electrons
- C. be reflected by direct contact with nuclei
- D. A and C
Correct Answer: D
Rationale: The correct answer is D because when alpha particles are beamed at a thin metal foil, some pass directly through due to their small size and high energy (option A), while others are reflected by direct contact with nuclei in the metal foil (option C). This is based on the Rutherford scattering experiment which showed that alpha particles can be deflected by the positive nuclei in the metal foil. Option B is incorrect as alpha particles are not diverted by attraction to electrons in the foil. Option D combines the correct explanations for the behavior of alpha particles when beamed at thin metal foil.
Convert 4338 mL to qt. (1 L = 06 qt)
- A. 4598 qt
- B. 4.092 qt
- C. 4.092 10 3 qt
- D. 4092 qt
Correct Answer: B
Rationale: To convert 4338 mL to qt, first convert mL to L by dividing by 1000 (4338 mL / 1000 = 4.338 L). Then, convert L to qt using the conversion factor 1 L = 0.946 qt. So, 4.338 L * 0.946 qt/L = 4.092 qt (Answer B).
Choice A (4598 qt) is incorrect as it does not follow the correct conversion process. Choice C (4.092 10 3 qt) is incorrect due to incorrect formatting and notation. Choice D (4092 qt) is incorrect as it uses the wrong conversion factor.
The melting point of indium is 2°C. At 323°F, what is the physical state of indium?
- A. Solid.
- B. Liquid.
- C. Gas.
- D. Not enough information.
Correct Answer: B
Rationale: To determine the physical state of indium at 323°F, we convert the temperature to Celsius (323°F = 161.7°C). Since the melting point of indium is 2°C, which is lower than 161.7°C, indium would be in a liquid state at 323°F. The correct choice is B: Liquid.
A: Solid - Incorrect because indium is in a liquid state at 323°F.
C: Gas - Incorrect, as indium would be in a liquid state at 323°F.
D: Not enough information - Incorrect since the temperature provided allows us to determine the physical state of indium.
The chemist credited for inventing a set of symbols for writing elements and a system for writing the formulas of compounds (and for discovering selenium, silicon, and thorium) is
- A. Boyle
- B. Lavoisier
- C. Priestly
- D. Berzelius
Correct Answer: D
Rationale: The correct answer is D: Berzelius. Berzelius is credited with inventing symbols for elements and a system for writing compound formulas. He also discovered selenium, silicon, and thorium. Berzelius made significant contributions to the field of chemistry.
A: Boyle is known for Boyle's Law related to gases, not for inventing chemical symbols or discovering elements.
B: Lavoisier is known as the father of modern chemistry but did not invent chemical symbols or discover these elements.
C: Priestly is known for discovering oxygen, but not for the specific contributions mentioned in the question.