Correct Answer: A

Rationale: To convert grams to milligrams, you multiply by 1000 since there are 1000 milligrams in a gram. Therefore, to convert 0.04 grams to milligrams, you would do 0.04 * 1000 = 40 mg. Choice A, '40 mg,' is the correct answer. Choices B, C, and D are incorrect because they do not correctly convert grams to milligrams. Choice B, '400 mg,' is incorrect because it mistakenly multiplies by 10 instead of 1000. Choice C, '4 mg,' is incorrect because it does not account for the correct conversion factor. Choice D, '0.4 mg,' is incorrect because it underestimates the conversion by a factor of 10.

Correct Answer: A

Rationale: A femtometer is equivalent to 10^-15 meters. The prefix 'femto-' signifies a factor of one quadrillionth (10^-15), making choice A the correct answer. Choice B (10^-9 meters) represents a nanometer, not a femtometer. Choice C (10^-12 meters) corresponds to a picometer, not a femtometer. Choice D (10^-18 meters) is even smaller than a femtometer and refers to an attometer, not a femtometer.

Correct Answer: A

Rationale: To convert kilograms to grams, you need to multiply by 1,000 since there are 1,000 grams in a kilogram. Therefore, 0.1 kg equals 100 grams. Choice B (10 g) is incorrect because it represents converting 0.01 kg to grams. Choice C (1 g) is incorrect as it reflects the conversion of 0.001 kg to grams. Choice D (0.1 g) is the value in grams equivalent to 0.01 kg, not 0.1 kg.

Correct Answer: A

Rationale: To convert 0.875 to a fraction, we write it as 875/1000. Then, simplify the fraction by dividing both the numerator and denominator by 125 to get 7/8, which is the simplest form of the fraction. Choice B (9/10), Choice C (5/6), and Choice D (3/4) are all incorrect because they do not represent the value of 0.875 when expressed as a fraction.

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.