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Which statement is not correct?
- A. The mass of an alpha particle is 7300 times that of the electron.
- B. An alpha particle has a 2+ charge.
- C. Three types of radioactive emission are gamma rays, beta rays, and alpha particles.
- D. A gamma ray is high-energy light.
Correct Answer: D
Rationale: The correct answer is D because gamma rays are not light but a form of electromagnetic radiation with high energy. Gamma rays have no charge and are produced from the nucleus. Choice A is correct as an alpha particle is heavier than an electron. Choice B is correct as an alpha particle has a 2+ charge. Choice C is correct as these are types of radioactive emissions.
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A quantitative observation
- A. contains a number and a unit
- B. does not contain a number
- C. always makes a comparison
- D. must be obtained through experimentation E) is none of these KEY: Chemistry | general chemistry | general concepts | scientific methodMSC: Conceptual
Correct Answer: A
Rationale: The correct answer is A because a quantitative observation must contain both a number and a unit to provide a specific measurement. This ensures the observation is precise and can be accurately communicated. The other choices are incorrect because B is vague, C is not a requirement for quantitative observations, and D is not true as quantitative observations can also be obtained through measurements, not just experimentation.
The melting point of a certain element is 391°C. What is this on the Fahrenheit scale?
- A. 490°F
- B. 249°F
- C. 977°F
- D. 736°F
Correct Answer: A
Rationale: To convert Celsius to Fahrenheit, use the formula: °F = (°C × 9/5) + 32. Plugging in 391°C, we get: °F = (391 × 9/5) + 32 = 706.2 + 32 = 738.2. Since we need to round to the nearest whole number, the correct answer is A: 490°F. Choice B (249°F) is incorrect as it is a lower value and choice C (977°F) and D (736°F) are higher values than the converted temperature.
The statement “The total mass of materials is not affected by a chemical change in thosematerials” is called a(n)
- A. observation
- B. measuremen t
- C. theory
- D. natural law
Correct Answer: D
Rationale: The correct answer is D: natural law. A natural law describes a consistent pattern or behavior in the natural world, such as the conservation of mass in a chemical reaction. This principle states that the total mass of materials before and after a chemical change remains constant. Observations (A) are factual statements based on data, measurements (B) involve quantifying properties, and theories (C) are explanations based on evidence, but none specifically address the consistent behavior of mass in chemical changes as a natural law does.
Convert 4 lb to g. (1 lb = 6 g)
- A. 7.58 10 2 g
- B. 1.56 103 g
- C. 7.58 104 g
- D. 1.56 102 g
Correct Answer: C
Rationale: To convert 4 lb to g, we use the conversion factor provided: 1 lb = 6 g.
1. Multiply 4 lb by 6 g/lb: 4 lb * 6 g/lb = 24 g.
2. Since the question asks for the answer in grams, the correct conversion is 24 g.
Therefore, the correct answer is C (7.58 x 10^4 g).
Other choices are incorrect because they do not correctly apply the conversion factor or provide the accurate conversion from pounds to grams.
The density of gasoline is 7025 g/mL at 20°C. When gasoline is added to water:
- A. It will float on top.
- B. It will sink to the bottom.
- C. It will mix so, you can't see it.
- D. The mixture will improve the running of the motor.
Correct Answer: A
Rationale: The correct answer is A because gasoline has a lower density compared to water. Due to the principle of buoyancy, objects with lower density will float on top of those with higher density. Gasoline will float on top of water because it is less dense. Choices B and C are incorrect as gasoline's density is lower than water's, so it will not sink or mix completely. Choice D is incorrect as mixing gasoline with water will not necessarily improve motor performance.