Correct Answer: A

Rationale: The correct answer is A: 10^-9 meters. 1 nanometer (nm) is equivalent to 10^-9 meters. This conversion is commonly used in various scientific fields, including nanotechnology, to represent extremely small lengths. Choice B, 10^-6 meters, is incorrect as it represents a micrometer, not a nanometer. Choice C, 10^-12 meters, is incorrect as it would be a picometer, which is smaller than a nanometer. Choice D, 10^-15 meters, is incorrect as it would be a femtometer, much smaller than a nanometer.

Correct Answer: B

Rationale: To convert milligrams to grams, you need to divide by 1,000 since there are 1,000 milligrams in 1 gram. Therefore, 5,000 milligrams is equal to 5 grams (5,000 · 1,000 = 5). Choice A, '50 grams,' is incorrect as it results from multiplying instead of dividing. Choice C, '500 grams,' is incorrect as it incorrectly multiplies the value. Choice D, '0.05 grams,' is incorrect as it is the result of dividing by 10 instead of 1,000.

Correct Answer: B

Rationale: The correct answer is B: 0.1 cm. One millimeter is equal to 0.1 centimeters, not 1/100th cm as mentioned in choice A. Choice C, 1 cm, is incorrect as a millimeter is smaller than a centimeter. Choice D, 10 cm, is incorrect as it incorrectly magnifies the conversion, making a millimeter larger than a centimeter. Therefore, the accurate conversion is that one millimeter equals 0.1 centimeters.

Correct Answer: A

Rationale: The decimal 0.07 can be expressed as the fraction 7/100, where 7 is the numerator and 100 is the denominator. To simplify the fraction, you divide both the numerator and denominator by their greatest common divisor, which in this case is 1. Therefore, 7/100 is already in its simplest form and cannot be further simplified. Choices B, C, and D are incorrect fractions as they do not represent the decimal 0.07.

Correct Answer: B

Rationale: To convert milliliters to liters, you need to divide by 1000 since there are 1000 milliliters in a liter. Therefore, 250 milliliters is equal to 250/1000 = 0.25 liters. Choice A, 25 liters, is incorrect as it is a magnitude higher than the correct answer. Choice C, 2.5 liters, is also incorrect as it is 10 times greater than the correct conversion. Choice D, 0.025 liters, is incorrect as it is a magnitude lower than the correct conversion.