Nokea
Consider the numbers 23.68 and 4.12. The sum of these numbers has
significant figures, and the product of these numbers has _
significant figures.
- A. 3, 3
- B. 4, 4
- C. 3, 4
- D. 4, 3
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).
You may also like to solve these questions
A metric unit for length is
- A. gram
- B. milliliter
- C. yard
- D. kilometer
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.
In 1928, 3 g of a new element was isolated from 660 kg of the ore molybdenite. The percent by mass of this element in the ore was:
- A. 44 %
- B. 6.6 %
- C. 29.3 %
- D. 0.0044 %
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.
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.
In 1984, some drums of uranium hexafluoride were lost in the English Channel, which is known for its cold water (about 17°C). The melting point of uranium hexafluoride is 148°F. In what physical state is the uranium hexafluoride in these drums?
- A. solid
- B. liquid
- C. gas
- D. a mixture of solid and liquid
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.
On a new temperature scale (°Z), water boils at 0°Z and freezes at 0°Z. Calculate the normal human body temperature using this temperature scale. On the Celsius scale, normal human body temperature could typically be 1°C, and water boils at 0°C and freezes at 00°C.
- A. 2968°Z
- B. 12.4°Z C)
- C. 111°Z
Correct Answer: A
Rationale: To calculate normal human body temperature in °Z, we can use the formula: °Z = (°C + 100) / 2. Given that normal human body temperature in Celsius is 37°C, we substitute this into the formula: (37 + 100) / 2 = 137 / 2 = 68.5°Z. Therefore, the correct answer is A: 2968°Z, as it is the closest to 68.5°Z.
Summary of other choices:
B: 12.4°Z - This is too low, as human body temperature is higher.
C: 111°Z - This is too high, as it exceeds the calculated value of 68.5°Z.