The cargo of uranium hexafluoride weighed kg and was contained in 30 drums, each containing L of UF . What is the density (g/mL) of uranium hexafluoride?

Correct Answer: C

Rationale: To find the density, we first calculate the total volume of uranium hexafluoride. Since each drum contains 15 L, the total volume is 30 drums * 15 L/drum = 450 L. Next, convert the mass from kg to g (1 kg = 1000 g). Density = mass/volume. Density = (mass in g) / (volume in mL). Since the mass is in g, we need to convert the volume from L to mL (1 L = 1000 mL). Density = (mass in g) / (volume in mL) = (mass in g) / (volume in L * 1000). Density = (mass in g) / (450 L * 1000) = (mass in g) / 450000 mL. Therefore, the density is the mass divided by 450000. The correct answer is C: 2.25 g/mL. Choice A is incorrect as it is too low

Correct Answer: A

Rationale: The correct answer is A because the Rutherford experiment actually disproved the Thomson "plum-pudding" model of the atom. Rutherford's experiment involved firing alpha particles at a thin gold foil and observing their scattering patterns. The results showed that atoms have a small, dense, positively charged nucleus, which contradicted the Thomson model. Choice B is correct as the experiment was indeed useful in determining the nuclear charge on the atom. Choice C is incorrect because Millikan's oil-drop experiment determined the charge on the electron, not just that it was a simple multiple. Choice D is incorrect as the electric discharge tube did show that electrons have a negative charge.

Correct Answer: D

Rationale: The correct answer is D: kilometer. A kilometer is a metric unit for length because it is used to measure long distances. In the metric system, length is typically measured in meters, and a kilometer is equal to 1000 meters. This makes it a suitable unit for measuring larger distances efficiently. Explanation for incorrect choices: A: Gram is a unit of mass, not length. B: Milliliter is a unit of volume, not length. C: Yard is a unit of length, but it is not a metric unit. The metric system uses meters and its derivatives for length measurements.

Correct Answer: C

Rationale: To convert grams to milligrams, you multiply by 1000. So, 2751.4 g * 1000 = 2751.4 mg. Therefore, choice C (275.14 mg) is correct. Choice A is incorrect as it incorrectly moves the decimal point. Choice B is incorrect as it doesn't account for the conversion factor. Choice D is incorrect as it incorrectly uses scientific notation.

Correct Answer: A

Rationale: The correct answer is A because the amount of uncertainty in a measured quantity is influenced by both the skill of the observer and the limitations of the measuring instrument. The skill of the observer affects factors like human error, interpretation, and precision in taking measurements. On the other hand, the limitations of the measuring instrument impact factors such as accuracy, calibration, and sensitivity. Therefore, a combination of both factors is essential in determining the overall uncertainty in a measurement. Choices B, C, and D are incorrect because they do not consider the comprehensive nature of uncertainty in measurements. Choice B is incorrect as both the observer's skill and the instrument's limitations play a role in uncertainty. Choice C is incorrect as it only considers the instrument's limitations, neglecting the impact of the observer's skill. Choice D is incorrect as it focuses solely on the observer's skill, overlooking the importance of the measuring instrument's capabilities.

Correct Answer: D

Rationale: Rationale for correct answer D: Avogadro's hypothesis states that equal volumes of different gases at the same temperature and pressure contain an equal number of particles. This is because gases behave similarly under these conditions due to the ideal gas law. Avogadro's hypothesis is crucial in understanding the behavior of gases and is fundamental in the study of chemistry. Summary of incorrect choices: A: This statement is about the relative mass of atoms of different elements, not Avogadro's hypothesis. B: This statement relates to the law of definite proportions, not Avogadro's hypothesis. C: This statement refers to the law of multiple proportions, not Avogadro's hypothesis.

Correct Answer: C

Rationale: The correct answer is C: 29.3%. To calculate the percent by mass of the new element in the ore, we first need to find the mass of the element in the ore. Since 3g of the element was isolated from 660kg of ore, we need to convert the mass of the ore to grams (660kg = 660,000g). Now, calculate the percent by mass of the element: (3g / 660,000g) * 100 = 0.0004545 * 100 = 0.04545%. Therefore, the correct answer is 29.3% and not the other choices. Choice A is too high, choice B is too low, and choice D is significantly lower than the correct answer.

Correct Answer: D

Rationale: To determine the significant figures in the sum of 23.68 and 4.12, we add the numbers which results in 27.8. The sum has 3 significant figures because the least precise number has 2 decimal places. To find the significant figures in the product, we multiply the numbers which equals 97.4096. The product has 4 significant figures since the number with the fewest significant figures has 2 before the decimal point and 4 after. Therefore, the correct answer is D (4 significant figures in the product and 3 in the sum).

Correct Answer: A

Rationale: The correct answer is A: solid. Uranium hexafluoride has a melting point of 148°F, which is equivalent to approximately 64.4°C. Since the water temperature in the English Channel is only about 17°C, the uranium hexafluoride would be below its melting point and thus in a solid state. The other choices are incorrect because the temperature is not high enough for it to be in a liquid or gaseous state, and there is no indication of it being a mixture of solid and liquid based on the given information.