Correct Answer: A

Rationale: To convert liters to milliliters, you need to multiply by 1000 since 1 liter is equal to 1000 milliliters. Therefore, 0.5 liters equals 500 milliliters. This conversion is commonly used in various fields such as cooking, medicine, and science. Choice B, 50 ml, is incorrect as it represents 0.05 liters, not 0.5 liters. Choice C, 5 ml, is even smaller and represents 0.005 liters. Choice D, 0.5 ml, is incorrect as it is a tenth of the correct conversion.

Correct Answer: A

Rationale: To convert 0.07 to a fraction, we note that 0.07 is equivalent to 7/100. This is because 0.07 can be read as 7 hundredths. Thus, the correct fraction form is 7/100. Choices B, C, and D are incorrect. Choice B, 1/10, is the fraction equivalent to 0.1, not 0.07. Choice C, 1/20, and Choice D, 1/50, are also incorrect as they do not represent the value of 0.07 when converted to a fraction.

Correct Answer: A

Rationale: The correct answer is A: 0.3 ml. To convert milligrams (mg) to milliliters (ml), you typically need the substance's density. However, in many medical contexts, especially with liquid medications similar in density to water, 0.3 mg is commonly assumed to be equivalent to 0.3 ml. Choice B (3 ml) is incorrect as it is 10 times greater than the correct conversion. Choice C (30 ml) is incorrect as it is 100 times greater than the correct conversion. Choice D (0.03 ml) is incorrect as it is one-tenth of the correct conversion.

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: B

Rationale: The correct answer is B: 100 cm. One meter is equivalent to 100 centimeters. This conversion is based on the metric system, where the prefix 'centi-' represents one hundredth. Choices A, C, and D are incorrect because they do not accurately reflect the conversion of meters to centimeters. Choice A, '1/10 cm,' is incorrect as it represents a fraction of a centimeter, not the full conversion from meters to centimeters. Choice C, '10 cm,' is incorrect as it represents the conversion from decimeters to centimeters, not meters to centimeters. Choice D, '1000 cm,' is incorrect as it represents the conversion from meters to millimeters, not centimeters.