Correct Answer: A

Rationale: To convert milliliters to liters, you need to divide by 1000 since there are 1000 milliliters in a liter. Therefore, 2500 milliliters divided by 1000 equals 2.5 liters, making choice A the correct answer. Choice B is incorrect because it incorrectly multiplies instead of dividing. Choice C is incorrect as it incorrectly places the decimal point, resulting in an incorrect conversion. Choice D is incorrect as it multiplies instead of dividing, leading to an inaccurate conversion.

Correct Answer: B

Rationale: The calculation of 0.4 divided by 40 results in 0.01, which can be expressed as 1/100. This fraction is the correct representation of the division of 0.4 by 40. Choice A, 1/100, is the correct answer as it accurately reflects the division. Choices C and D, 1/400 and 1/40000 respectively, do not correctly represent the division operation performed on 0.4 and 40, leading to incorrect results and are therefore not the correct answers.

Correct Answer: B

Rationale: To convert milliliters to liters, you need to divide by 1000 since 1 liter is equal to 1000 milliliters. Therefore, 500 milliliters divided by 1000 equals 0.5 liters. Choice A (0.05 liters) is incorrect because it represents 50 milliliters, not 500 milliliters. Choice C (5 liters) and Choice D (50 liters) are both incorrect as they are higher values and do not accurately represent the conversion of 500 milliliters to liters.

Correct Answer: A

Rationale: To convert milligrams to micrograms, you need to multiply by 1000 because there are 1000 micrograms in 1 milligram. Therefore, 0.15 mg is equal to 150 mcg. Choice B (15 mcg) is incorrect as it represents the conversion of 0.015 mg to mcg. Choice C (1.5 mcg) is incorrect as it represents the conversion of 0.0015 mg to mcg. Choice D (1500 mcg) is incorrect as it represents the conversion of 1.5 mg to mcg. So, the correct answer is 150 mcg, a conversion often used in medical dosing.

Correct Answer: D

Rationale: The correct SI conversion for grams (g) to milligrams (mg) is 1 g = 1000 mg, not 100 mg. Therefore, option D is incorrect. Option A is correct as 1 cm is equal to 10 mm, option B is correct as 1 m equals 100 cm, and option C is correct as 1 km is equivalent to 1000 m. Understanding these basic SI conversions is essential for accurate measurements and calculations in various scientific fields.