Correct Answer: A

Rationale: The correct answer is 'millimeter' (A). 'mm' stands for millimeter, which is equal to one-thousandth of a meter. Choice B, 'megabyte,' is a unit of digital information storage, not a metric system unit. Choice C, 'millipede,' is an arthropod and not a metric unit. Choice D, 'metered,' is not a standard metric unit abbreviation.

Correct Answer: A

Rationale: To convert milligrams (mg) to micrograms (mcg), you need to multiply by 1000 because there are 1000 micrograms in 1 milligram. Therefore, 0.2 mg * 1000 = 200 mcg. This is the correct conversion. Choice B (20 mcg) is incorrect because it does not account for multiplying by 1000. Choice C (2000 mcg) is incorrect as it mistakenly multiplies by 10 instead of 1000. Choice D (2 mcg) is incorrect as it does not involve any conversion from milligrams to micrograms.

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.

Correct Answer: A

Rationale: In the metric system, 'L' stands for liter, which is the base unit for liquid volume. The other choices are incorrect: 'B' log is not a standard metric unit, 'C' link is a unit of length in the Imperial system, and 'D' lever is not a metric unit but a simple machine.

Correct Answer: A

Rationale: 0.5 liters is equivalent to 500 milliliters. The conversion from liters to milliliters involves multiplying by 1000 since there are 1000 milliliters in a liter. Therefore, the correct answer is 500 ml. Choices B, C, and D are incorrect because they do not correctly convert liters to milliliters. 50 ml is the conversion for 0.05 liters, 5 ml for 0.005 liters, and 0.5 ml for 0.0005 liters.