Correct Answer: A

Rationale:
To convert milligrams to micrograms, you need to multiply by 1000, not 10000.
Therefore, 0.025 mg is equal to 25 mcg. The correct conversion is obtained by recognizing that 1 milligram (mg) is equal to 1000 micrograms (mcg).

Choices B, C, and D are incorrect because they do not correctly convert milligrams to micrograms.
Choice B is 10 times the correct answer, choice C is 100 times less, and choice D is 100 times less than the correct conversion.

Correct Answer: A

Rationale: In the metric system, 'km' stands for kilometer, which is a unit of length equal to 1,000 meters. This choice is correct as 'kilometer' is the standard unit for measuring long distances.
Choice B, 'kilomole,' is incorrect as it is a unit in chemistry representing a quantity of substance.
Choice C, 'kilobyte,' is incorrect as it is a unit of digital information storage, not a unit of measurement.
Choice D, 'knot,' is incorrect as it is a unit of speed used in navigation and aeronautics, not a unit of length in the metric system.

Correct Answer: B

Rationale:
To convert liters to milliliters, you need to multiply the number of liters by 1000 because there are 1000 milliliters in 1 liter.
Therefore, 0.5 liters converts to 500 milliliters.
Choice A (50 ml) is incorrect as it is the result of multiplying by 10 instead of 1000.
Choice C (5 ml) is incorrect as it is the result of dividing by 10 instead of multiplying by 1000.
Choice D (0.5 ml) is incorrect as it represents the original quantity in milliliters, not the conversion from liters.

Correct Answer: D

Rationale: The correct answer is D: Exact Equivalent. The expression 1 inch = 2.54 cm is a direct and precise conversion between inches and centimeters, making it an exact equivalent. It is not related to the Law of Conservation of Units (
A) as this principle pertains to the conservation of physical quantities in a system. The International Yard (
B) is a unit of measurement, but it is not the term for the given expression. Similarly, while the conversion factor in the expression is standard, it is specifically an exact equivalent and not just a general standard conversion factor (
C).
Therefore, D is the most appropriate term to describe this specific conversion relationship.

Correct Answer: B

Rationale:
To convert 0.2 liters to milliliters, you need to multiply by 1000 because there are 1000 milliliters in 1 liter.
Therefore, 0.2 liters x 1000 = 200 ml.
Choice A (20 ml) is incorrect because it represents 0.02 liters, not 0.2 liters.
Choice C (2 ml) is incorrect as it represents 0.002 liters.
Choice D (2000 ml) is incorrect as it represents 2 liters, not 0.2 liters.