Correct Answer: A

Rationale: To convert milligrams to micrograms, you need to multiply by 1000 because there are 1000 micrograms in a milligram. Therefore, 0.025 mg x 1000 = 25 mcg. This means that the correct answer is A, 25 mcg. Choice B, 250 mcg, is incorrect because it incorrectly multiplies by 10 instead of 1000. Choice C, 2.5 mcg, is incorrect as it inaccurately divides the value by 10. Choice D, 0.25 mcg, is also incorrect as it divides the value by 100 instead of multiplying by 1000.

Correct Answer: B

Rationale: The metric system was developed in France during the 1790s as a standardized system of measurement. This choice is correct because the metric system originated in France. Germany, Italy, and Spain did not play a role in the development of the metric system, making choices A, C, and D incorrect.

Correct Answer: A

Rationale: The mnemonic 'King Hector Died By Drinking Chocolate Milk' aids in recalling metric prefixes in order: kilo-, hecto-, deca-, base (meter, liter, gram), deci-, centi-, milli-. Choice B does not provide a relevant mnemonic for metric conversions. Choices C and D do not offer a helpful phrase for remembering metric prefixes, making them incorrect.

Correct Answer: A

Rationale: To convert milligrams (mg) to micrograms (mcg), you multiply by 1000 because 1 mg is equal to 1000 mcg. Therefore, 0.25 mg is equal to 250 mcg. Choices B, C, and D are incorrect as they do not consider the correct conversion factor.

Correct Answer: B

Rationale: To convert kilometers to meters, you need to multiply by 1,000 since there are 1,000 meters in a kilometer. Therefore, 345 km multiplied by 1,000 equals 345,000 meters. Choice A is incorrect as it incorrectly places the comma. Choice C is incorrect as it adds an extra zero at the end. Choice D is incorrect as it adds an extra zero at the beginning, resulting in an incorrect conversion.