Correct Answer: B

Rationale: To convert grams to milligrams, you need to multiply by 1,000 since there are 1,000 milligrams in a gram. Therefore, 3,450 grams 1,000 = 3,450,000 milligrams. Choice A (34,500 mg) is incorrect because it represents the result for converting grams to milligrams by a factor of 10 (not 1,000). Choice C (3,450 mg) is incorrect as it represents the original amount in grams, not the converted amount to milligrams. Choice D (3,450,000 mg) is incorrect as it is the same as the correct answer but with the comma in the wrong place, which would imply converting kilograms to milligrams rather than grams to milligrams.

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, 345 cm · 100,000 = 0.00345 km. The correct answer is 0.0345 km, which is obtained by accurately dividing 345 by 100,000. Choices A, C, and D are incorrect because they do not correctly apply the conversion factor and result in inaccurate values for kilometers.

Correct Answer: B

Rationale: The correct answer is B: 2 liters. To convert milliliters to liters, you need to divide by 1000 since there are 1000 milliliters in a liter. Therefore, 2,000 milliliters is equal to 2 liters (2000 · 1000 = 2). Choices A, C, and D are incorrect because they incorrectly convert milliliters to liters, resulting in values that are too low (A and C) or too high (D).

Correct Answer: B

Rationale: The decimal 0.2 is already at the nearest tenth, so it does not need to be rounded. Rounding to the nearest tenth means keeping one decimal place, which is already the case with 0.2. Therefore, the correct answer is 0.2, as it is already at the specified rounding point. Choices A, C, and D are incorrect because they represent values that are not the result of rounding 0.2 to the nearest tenth. 0.1 is rounding down, 0.3 is rounding up, and 0.25 is not the nearest tenth of 0.2.

Correct Answer: B

Rationale: To convert kilograms to grams, you need to multiply by 1000 since there are 1000 grams in a kilogram. Therefore, 2 kilograms is equal to 2 x 1000 = 2000 grams. Choice A (200 grams) is incorrect as it represents the value of 0.2 kilograms. Choice C (20 grams) is incorrect as it represents the value of 0.02 kilograms. Choice D (2 grams) is incorrect as it represents the value of 0.002 kilograms.