Correct Answer: B

Rationale: The correct answer is B: '10 mm'. There are 10 millimeters in 1 centimeter. To convert centimeters to millimeters, you multiply by 10 because 1 centimeter is equivalent to 10 millimeters. Choice A '1 mm' is incorrect as it represents the size of 1 millimeter, not the conversion from centimeters to millimeters. Choice C '100 mm' is incorrect as it is the equivalent of 1 meter, not 1 centimeter. Choice D '1,000 mm' is incorrect as it is the equivalent of 1 meter, not 1 centimeter.

Correct Answer: A

Rationale: To convert 0.004 to a ratio, we can express it as 4/1000, which simplifies to 1/250. Therefore, the correct ratio is 1:250. Choice B (4:200) is incorrect as it simplifies to 1:50, not 1:250. Choice C (2:400) simplifies to 1:200, which is also incorrect. Choice D (9:200) simplifies to a ratio greater than 1:1, which is not equivalent to 1:250.

Correct Answer: A

Rationale: To convert milligrams to micrograms, you need to multiply by 1000 because there are 1000 micrograms in 1 milligram. Therefore, 0.5 mg x 1000 = 500 mcg. This conversion is crucial in medication dosage calculations to ensure precise administration. Choice B, 50 mcg, is incorrect as it represents 0.05 mg. Choice C, 5 mcg, is incorrect as it corresponds to 0.005 mg. Choice D, 0.5 mcg, is incorrect because it is the same value as the initial amount in milligrams, rather than the converted value to micrograms.

Correct Answer: B

Rationale: The correct answer is B: 128 ounces. One gallon is equivalent to 128 ounces. This conversion relationship is commonly used in cooking, baking, and various liquid measurements. Choice A (64 ounces) is incorrect as it represents half the amount of a gallon. Choice C (100 ounces) and Choice D (150 ounces) are also incorrect, as they do not accurately reflect the conversion of a gallon to ounces.

Correct Answer: B

Rationale: The correct answer is B: derived units. When base units (such as grams or milliliters) are combined, as seen in g/mL (grams per milliliter) for density, they form derived units. Derived units measure complex quantities that are derived from combinations of base units. Choice A, 'combined units,' is incorrect as it does not specifically refer to the formation of new units from base units. Choice C, 'base units,' is incorrect because base units are the fundamental units from which all other units are derived, not the combinations of units. Choice D, 'calculated units,' is incorrect as it does not accurately describe the concept of combining base units to form a new unit like g/mL for density.