Correct Answer: B

Rationale: To convert meters to centimeters, you need to multiply by 100 since there are 100 centimeters in a meter. Therefore, 0.25 meters x 100 = 25 centimeters. Choice A, '2.5 cm,' is incorrect as it is the result of multiplying by 10 instead of 100. Choice C, '250 cm,' is incorrect as it is the result of multiplying by 1000. Choice D, '0.25 cm,' is incorrect as it suggests the conversion is in the opposite direction, from centimeters to meters.

Correct Answer: B

Rationale: 0.3 milliliters is equivalent to 0.3 ml. This is a precise measurement commonly used in medical settings for administering small doses of liquid medication. It is important to understand and recognize the decimal point placement when converting between milliliters and other volume units. Choice A (0.03 ml) is incorrect as it represents a smaller amount than 0.3 ml. Choice C (3 ml) and Choice D (30 ml) are also incorrect as they are larger measurements and do not match the given amount of 0.3 ml.

Correct Answer: B

Rationale: The correct answer is B: derived units. When base units (such as grams or milliliters) are combined, as seen in g/mL (grams per milliliter) for density, they form derived units. Derived units measure complex quantities that are derived from combinations of base units. Choice A, 'combined units,' is incorrect as it does not specifically refer to the formation of new units from base units. Choice C, 'base units,' is incorrect because base units are the fundamental units from which all other units are derived, not the combinations of units. Choice D, 'calculated units,' is incorrect as it does not accurately describe the concept of combining base units to form a new unit like g/mL for density.

Correct Answer: A

Rationale: The correct answer is 'meter.' In the metric system, 'm' stands for meter, which is the base unit for length. Choice B, 'mole,' is a unit used in chemistry to represent an amount of substance. Choice C, 'milli,' represents a prefix indicating one-thousandth, and choice D, 'micro,' represents a prefix indicating one-millionth. Therefore, the correct choice is 'A: meter.'

Correct Answer: A

Rationale: To convert milligrams to micrograms, you need to multiply by 1000, not 10000. Therefore, 0.025 mg is equal to 25 mcg. The correct conversion is obtained by recognizing that 1 milligram (mg) is equal to 1000 micrograms (mcg). Choices B, C, and D are incorrect because they do not correctly convert milligrams to micrograms. Choice B is 10 times the correct answer, choice C is 100 times less, and choice D is 100 times less than the correct conversion.