Correct Answer: B

Rationale: To convert kilograms to grams, you need to multiply by 1000 since there are 1000 grams in 1 kilogram. Therefore, 0.5 kilograms is equal to 500 grams (0.5 x 1000 = 500). Choice A (50 grams) is incorrect as it is the result of multiplying by 10 instead of 1000. Choice C (5,000 grams) is incorrect as it is the result of adding an extra zero. Choice D (0.5 grams) is incorrect as it represents the original amount in grams, not the converted amount.

Correct Answer: A

Rationale: To convert grams to milligrams, you need to multiply by 1000, not 10000. Therefore, to convert 0.04 grams to milligrams, you multiply 0.04 by 1000, which equals 40 mg. Choice A (40 mg) is the correct answer. Choice B (4 mg) is incorrect as it represents converting 0.004 grams to milligrams. Choice C (400 mg) is incorrect as it is 10 times the correct conversion. Choice D (0.4 mg) is incorrect as it is 10 times smaller than the correct conversion.

Correct Answer: A

Rationale: To convert milligrams to micrograms, you multiply by 1000, not 10000. Therefore, 0.025 mg equals 25 mcg. Choice B (250 mcg) is incorrect as it incorrectly multiplies by 10000. Choice C (2.5 mcg) is incorrect as it incorrectly divides by 10. Choice D (0.25 mcg) is incorrect as it incorrectly multiplies by 10.

Correct Answer: B

Rationale: The metric system is based on powers of 10. This means that units within the system are related by factors of 10, making conversions straightforward by simply shifting the decimal point. The system's simplicity and consistency are derived from this fundamental concept. Choices A, C, and D are incorrect because the metric system's foundation lies in the consistent relationship between units through powers of 10, not through basic arithmetic operations like multiplication, addition, or subtraction.

Correct Answer: D

Rationale: To convert pounds to kilograms, you need to divide the weight in pounds by 2.205 (1 kg = 2.205 lbs). Therefore, 255.0 pounds divided by 2.205 equals 115.6 kilograms. This results in choice D being the correct answer. Choices A, B, and C are incorrect as they do not reflect the accurate conversion calculation from pounds to kilograms.