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: B

Rationale: The correct answer is B: 5280 feet. One mile is equivalent to 5280 feet. This is a standard conversion that is widely known. Choice A (5000 feet) is incorrect as it is not the exact conversion of a mile. Choice C (5300 feet) and choice D (5500 feet) are also incorrect as they do not represent the accurate conversion from miles to feet.

Correct Answer: A

Rationale: To convert liters to milliliters, you need to multiply by 1000 since 1 liter is equal to 1000 milliliters. Therefore, 0.5 liters multiplied by 1000 equals 500 milliliters. Choice A, 500 mL, is the correct answer. Choice B, 50 mL, is incorrect as it represents converting 0.05 liters to milliliters. Choice C, 5 mL, is incorrect as it represents converting 0.005 liters to milliliters. Choice D, 0.5 mL, is incorrect as it represents the original amount in milliliters, not the conversion of liters to milliliters.

Correct Answer: A

Rationale: Density is measured in grams per cubic meter (g/m³) in the metric system. This unit represents the amount of mass (in grams) per unit volume (cubic meter). Choice B, grams per liter (g/L), is incorrect as density is not typically measured in liters. Choice C, grams per cubic centimeter (g/cm³), is a common unit for density but not the standard SI unit. Choice D, grams per square meter (g/m²), is a unit for surface density, not volumetric density. Therefore, the correct unit for measuring density in the metric system is grams per cubic meter (g/m³).

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.