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: A

Rationale: The correct formula to convert Celsius to Fahrenheit is (C 9/5) + 32. This formula involves multiplying the Celsius temperature by 9/5 and then adding 32 to get the Fahrenheit temperature. Choice B is incorrect as it suggests dividing by 5/9 instead of multiplying by 9/5. Choices C and D are both incorrect because they involve using the Fahrenheit temperature in the calculation, which is not the correct method for converting Celsius to Fahrenheit.

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: The base unit for mass in the metric system is grams. Grams are the fundamental unit of mass in the metric system, representing smaller quantities than kilograms and tons. Milligrams are a smaller unit of mass, kilograms are a larger unit, and tons are even larger units. Therefore, the correct choice is grams.

Correct Answer: A

Rationale: The correct answer is A: 1760 yards. There are 1760 yards in one mile. This conversion is a standard unit of measurement in the imperial system. Choice B, 1500 yards, is incorrect as it is not the correct conversion from miles to yards. Choice C, 2000 yards, is also incorrect as it does not represent the accurate conversion. Choice D, 1800 yards, is incorrect as it does not reflect the correct number of yards in a mile according to the established conversion rate.