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.

Correct Answer: A

Rationale: The metric prefix 'centi-' signifies 10^-2, denoting one-hundredth of a unit. For instance, 1 centimeter equals 0.01 of the base unit. Choice B, 'milli,' represents 10^-3, 'nano' in Choice C represents 10^-9, and 'deci' in Choice D stands for 10^-1. Therefore, the correct answer is 'centi.'

Correct Answer: B

Rationale: The correct answer is B: 2 pints. There are 2 pints in one quart. A quart is equivalent to 2 pints, so each quart contains 2 pints. Choice A, 1 pint, is incorrect because a quart consists of more than 1 pint. Choice C, 3 pints, and Choice D, 4 pints, are also incorrect as they do not accurately represent the conversion of quarts to pints.

Correct Answer: D

Rationale: To convert millimeters to centimeters, you need to divide by 10 because there are 10 millimeters in one centimeter. Therefore, 25 millimeters is equal to 25/10 = 2.5 centimeters, making choice D the correct answer. Choice A (250 cm) is incorrect as it incorrectly multiplies instead of dividing by 10. Choice B (25 cm) is also incorrect as it doesn't convert millimeters to centimeters. Choice C (2.5 mm) is incorrect as it provides the measurement in millimeters rather than centimeters.

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.