Nokea
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.
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During a physics experiment, an electron is accelerated to 93 percent of the speed of light. What is the speed of the electron in miles per hour? (speed of light = 00 108 m/s, 1 km = 6214 mi)
- A. 2.8 108 mi/h
- B. 6.2 1011 mi/h
- C. 6.7 108 mi/h
- D. 1.0 107 mi/h
Correct Answer: C
Rationale: The correct answer is C: 6.7 x 10^8 mi/h. To calculate the speed of the electron in miles per hour, we first convert the speed of light from m/s to mi/h using the conversion factor 1 km = 6214 mi. The speed of light is approximately 6.71 x 10^8 mi/h. Since the electron is at 93% of the speed of light, we multiply the speed of light by 0.93 to get the speed of the electron, which is approximately 6.25 x 10^8 mi/h. The closest choice is C: 6.7 x 10^8 mi/h.
Choice A: 2.8 x 10^8 mi/h - This is incorrect as it is too low compared to the calculated speed.
Choice B: 6.2 x 10^11 mi/h - This is incorrect as it is too high compared to the calculated speed.
Choice
You measure water in two containers: a 10-mL graduated cylinder with marks at every mL, and a 1-mL pipet marked at every 1 mL. If you have some water in each of the containers and add them together, to what decimal place could you report the total volume of water?
- A. 0.01 mL
- B. 0.1 mL
- C. 1 mL
- D. 10 mL
Correct Answer: C
Rationale: The correct answer is C: 1 mL. When adding volumes measured in different containers, you should report the result to the least precise measurement scale, which is the 1 mL pipet in this case. The graduated cylinder measures to the nearest mL, so the total volume should be rounded to the nearest whole mL. Reporting to a decimal place of 0.01 mL or 0.1 mL would imply a level of precision greater than what the equipment can provide. Choice D is incorrect as it exceeds the maximum volume capacity of the containers and is not relevant to the precision of the measurements.
Convert 9 kg to lb. (1 kg = 205 lb)
- A. 17 lbs
- B. 1.7 lbs
- C. 3.6 lbs
- D. 0.017 lbs
Correct Answer: A
Rationale: To convert 9 kg to lb, we multiply 9 kg by the conversion factor of 2.205 lb/kg.
9 kg * 2.205 lb/kg = 19.845 lb, which is approximately 20 lb.
Among the choices, 17 lbs (option A) is the closest to 20 lb, making it the correct answer.
Option B (1.7 lbs), C (3.6 lbs), and D (0.017 lbs) are all significantly lower and do not match the conversion calculation.
20 protons
- A. 22 protons
- B. 20 protons
- C. 18 electrons
- D. 22
Correct Answer: A
Rationale: The correct answer is A. Since the question states that there are 20 protons, option A with 22 protons is incorrect. Option B with 20 protons matches the given information, making it the correct answer. Option C with 18 electrons is unrelated to the given information about protons. Option D with just the number 22 is irrelevant and does not provide any information about protons.
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.