Correct Answer: A

Rationale: To convert grams to kilograms, divide by 1,000 since there are 1,000 grams in a kilogram. Therefore, 34.5 grams · 1,000 = 0.0345 kilograms. The correct answer is 3.45 kg (not 3.45 grams, which is the amount given in the initial question). Choices B and C are incorrect as they do not involve the conversion from grams to kilograms. Choice D is also incorrect as it presents the value in grams instead of kilograms.

Correct Answer: A

Rationale: To convert liters to milliliters, you multiply the number of liters by 1000. Therefore, 0.5 liters equals 500 milliliters. This conversion is standard in various fields, making choice A the correct answer. Choices B, C, and D are incorrect because they do not correctly convert liters to milliliters.

Correct Answer: C

Rationale: The correct answer is C: 1,000 grams. The metric system follows a logical conversion where 1 kilogram is equal to 1,000 grams. This conversion is a fundamental concept in understanding units of measurement. Choices A, B, and D are incorrect because they do not accurately reflect the conversion between kilograms and grams. Option A (10 grams) is incorrect as it represents 1/100th of the correct conversion. Option B (100 grams) is also incorrect as it represents 1/10th of the correct conversion. Option D (10,000 grams) is significantly higher than the actual conversion, making it incorrect. Understanding these basic unit conversions is essential for various fields where precise measurements are necessary.

Correct Answer: B

Rationale: The correct answer is B: Liters. In the metric system, liters are the base unit for liquid volume. Milliliters, though a metric unit, are a smaller unit of volume and not the base unit. Gallons, on the other hand, are part of the imperial system and not a metric unit for volume. Option D is a duplicate of option B, making it incorrect.

Correct Answer: B

Rationale: A balance scale is specifically designed to measure the mass of an object in grams or kilograms. It works based on the principle of balancing the unknown mass against a known mass. A thermometer is used to measure temperature, not mass, so choice A is incorrect. Choice C, 'scale,' is a bit vague and can refer to different types of scales, but a balance scale is the specific instrument used for measuring mass. Choice D, 'caliper,' is used for measuring dimensions such as length, width, or thickness, not mass.