Correct Answer: B

Rationale: The correct answer is B: 3 feet. This is because 1 yard is equivalent to 3 feet. The conversion factor between yards and feet is 1 yard = 3 feet. Choice A (4 feet) is incorrect as it represents the conversion of 1 yard to 4 feet, which is inaccurate. Choice C (2 feet) is incorrect as it underestimates the number of feet in 1 yard. Choice D (5 feet) is incorrect as it overestimates the number of feet in 1 yard.

Correct Answer: A

Rationale: To convert liters to milliliters, you need to multiply by 1000 since there are 1000 milliliters in 1 liter. So, 0.20 liters x 1000 = 200 milliliters. This makes choice A, '200 ml,' the correct answer. Choices B, C, and D are incorrect because they do not reflect the correct conversion factor from liters to milliliters.

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: A

Rationale: To convert liters to milliliters, you need to multiply by 1000 since there are 1000 milliliters in a liter. Therefore, 0.5 liters is equal to 500 milliliters. Choices B, C, and D are incorrect because they do not reflect the correct conversion from liters to milliliters.

Correct Answer: A

Rationale: The correct answer is A: 500 ml. To convert liters to milliliters, you multiply the number of liters by 1000 because 1 liter is equal to 1000 milliliters. Therefore, 0.5 liters x 1000 = 500 milliliters. Choices B, C, and D are incorrect because they do not correctly convert 0.5 liters to milliliters based on the conversion factor of 1000 ml per liter.