Correct Answer: B

Rationale: To convert centimeters to kilometers, you need to divide by 100,000 since there are 100,000 centimeters in a kilometer. Therefore, 35.4 cm · 100,000 = 0.000354 km. Choice A (0.00354 km) is incorrect as it represents dividing by 10,000, not 100,000. Choice C (0.00345 km) is incorrect as the last digit is different from the correct answer. Choice D (0.0345 km) is incorrect as it represents dividing by 1,000, not by 100,000.

Correct Answer: D

Rationale: The correct answer is D: 1,000 mg. This is because 1 gram is equivalent to 1,000 milligrams. To convert grams to milligrams, you multiply by 1,000. Choices A, B, and C are incorrect. Choice A (1 mg) is the smallest unit, and it would take 1,000 of these to make 1 gram. Choice B (10 mg) is also too small, as it would require 100 of these to equal 1 gram. Choice C (100 mg) is closer, but it still falls short of the correct conversion, which is 1,000 mg in 1 gram.

Correct Answer: B

Rationale: The base unit for mass in the metric system is grams. Grams are the fundamental unit of mass in the metric system, representing smaller quantities than kilograms and tons. Milligrams are a smaller unit of mass, kilograms are a larger unit, and tons are even larger units. Therefore, the correct choice is grams.

Correct Answer: A

Rationale: The correct answer is A: 1760 yards. There are 1760 yards in one mile. This conversion is a standard unit of measurement in the imperial system. Choice B, 1500 yards, is incorrect as it is not the correct conversion from miles to yards. Choice C, 2000 yards, is also incorrect as it does not represent the accurate conversion. Choice D, 1800 yards, is incorrect as it does not reflect the correct number of yards in a mile according to the established conversion rate.

Correct Answer: B

Rationale: The correct answer is B: 1000 grams. This is because by definition, 1 kilogram is equal to 1000 grams. Choice A, 100 grams, is incorrect as it underestimates the actual conversion. Choice C, 500 grams, and Choice D, 2000 grams, are also incorrect as they do not align with the correct conversion factor of 1 kilogram to 1000 grams.