Nokea
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.
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Convert 4 mi to km. (1 m = 094 yd, 1 mi = 1760 yd)
- A. 6.50 101 km
- B. 3.69 101 km
- C. 9.56 107 km
- D. 5.43 101 km
Correct Answer: B
Rationale: To convert 4 mi to km, first convert miles to yards: 4 mi * 1760 yd/mi = 7040 yd. Then convert yards to meters: 7040 yd * 0.9144 m/yd = 6437.216 m. Finally, convert meters to kilometers: 6437.216 m/1000 m/km = 6.437216 km. Rounding to three significant figures, the answer is 3.69 x 10^1 km (B). Other choices are incorrect because they do not correctly convert miles to kilometers or have calculation errors.
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.
What was the price of London petrol in dollars ($) per gallon? (1 gal = 7854 L)
- A. $4.46 /gal
- B. $2.20 /gal
- C. $9.05 /gal
- D. $1.58 /gal
Correct Answer: B
Rationale: The correct answer is B: $2.20 /gal. To convert the price of London petrol given in British pounds to dollars per gallon, we first need to convert the price from pounds to dollars using the current exchange rate. Then, we convert the price per liter to price per gallon by multiplying by the conversion factor (1 gal = 3.7854 L). The conversion results in $2.20 /gal.
Choice A ($4.46 /gal) is incorrect because it is not the correct conversion of the given price. Choice C ($9.05 /gal) is incorrect as it is too high based on the correct conversion. Choice D ($1.58 /gal) is incorrect as it does not accurately reflect the conversion from pounds to dollars and liters to gallons.
Which of the following metric relationships is incorrect?
- A. 1 microliter = 10–6 liters
- B. 1 gram = 103 kilograms
- C. 103 milliliters = 1 liter
- D. 1 gram = 102 centigrams
Correct Answer: B
Rationale: The correct answer is B: 1 gram = 10^3 kilograms. This is incorrect because 1 kilogram is equal to 1000 grams, not 100 grams. A is correct as 1 microliter is indeed 10^-6 liters. C is correct as 10^3 milliliters equals 1 liter. D is correct as 1 gram is equal to 10^2 centigrams. The incorrect relationship in choice B violates the metric system conversion factor of 1 kilogram being equal to 1000 grams.
You are asked to determine the perimeter of the cover of your textbook. You measure the length as 36 cm and the width as 83 cm. How many significant figures should you report for the perimeter?
- A. 1
- B. 2
- C. 3
- D. 4
Correct Answer: C
Rationale: The correct answer is C (3 significant figures). When calculating the perimeter of a rectangle, you add all the sides together. In this case, the perimeter would be 2(36 cm + 83 cm) = 238 cm. The least precise measurement given (83 cm) has 2 significant figures. Therefore, the final answer should be reported with the same number of significant figures as the least precise measurement, which is 3.
Summary:
A: 1 significant figure is too few.
B: 2 significant figures are based on the least precise measurement.
D: 4 significant figures are too many as it should match the least precise measurement.