The degree of agreement among several measurements of the same quantity is called . It reflects the reproducibility of a given type of measurement.

Correct Answer: C

Rationale: The correct answer is C: precision. Precision refers to the degree of agreement among repeated measurements of the same quantity. It reflects how close the measurements are to each other, indicating reproducibility. Accuracy (choice A) is about how close a measurement is to the true value, not the agreement among multiple measurements. Error (choice B) is a deviation from the true value and not specifically related to the agreement among measurements. Significance (choice D) is about the importance or relevance of a result, not the consistency of measurements. Therefore, precision is the most appropriate term in this context.

Correct Answer: A

Rationale: The correct answer is A: accuracy. Accuracy refers to how close a measured value is to the true value. It indicates the absence of systematic errors. Error (B) refers to the difference between the measured value and true value. Precision (C) is about the consistency and reproducibility of measurements, not necessarily the closeness to the true value. Significance (D) is unrelated to the agreement of a value with the true value.

Correct Answer: A

Rationale: The correct answer is A: 107.8°F. To convert Celsius to Fahrenheit, you use the formula °F = (°C x 9/5) + 32. Substituting 5°C into the formula gives (5 x 9/5) + 32 = 41 + 32 = 73°F. Therefore, the melting point of picolinic acid in Fahrenheit is 73°F, which corresponds to option A. Option B, C, and D are incorrect because they do not match the calculated Fahrenheit temperature.

Correct Answer: B

Rationale: To convert 4 mi to km, first convert miles to yards: 4 mi * 1760 yd/mi = 7040 yd. Then convert yards to meters: 7040 yd * 0.9144 m/yd = 6437.216 m. Finally, convert meters to kilometers: 6437.216 m/1000 m/km = 6.437216 km. Rounding to three significant figures, the answer is 3.69 x 10^1 km (B). Other choices are incorrect because they do not correctly convert miles to kilometers or have calculation errors.

Correct Answer: A

Rationale: The correct answer is A because it involves a measurable quantity (length) that can be expressed numerically. This is a quantitative observation as it can be described with numbers. Choices B and C describe qualities (color and appearance) which are qualitative observations. Choice D provides a quantitative measurement (temperature) but it is not an observation, rather a measurement.

Correct Answer: C

Rationale: The correct answer is C: precision. Precision refers to the degree of agreement among repeated measurements of the same quantity. It reflects how close the measurements are to each other, indicating reproducibility. Accuracy (choice A) is about how close a measurement is to the true value, not the agreement among multiple measurements. Error (choice B) is a deviation from the true value and not specifically related to the agreement among measurements. Significance (choice D) is about the importance or relevance of a result, not the consistency of measurements. Therefore, precision is the most appropriate term in this context.

Correct Answer: A

Rationale: The correct answer is A: Ions are formed by adding or removing protons or electrons. This statement is true because ions are formed when an atom gains or loses one or more electrons, resulting in a positive or negative charge. This process does not involve changing the number of protons in the nucleus. Choice B is incorrect because solids are composed of closely packed atoms or molecules, not open space. Choice C is incorrect because heating water with a Bunsen burner does not result in a 2:1 mixture of hydrogen and oxygen gases, but rather breaks down water into hydrogen and oxygen molecules. Choice D is incorrect as only statement A is true.

Correct Answer: D

Rationale: To convert cm3 to liters, divide by 1000 as 1 liter = 1000 cm3. Therefore, 781.2 cm3 ÷ 1000 = 0.7812 L. Correct answer is D: 0.7812 L. Other choices are incorrect as they do not reflect the correct conversion from cm3 to liters.

Correct Answer: C

Rationale: The correct answer is C: Mg2+. A species with 12 protons must have an atomic number of 12, which corresponds to magnesium (Mg). The 10 electrons indicate that it has a 2+ charge, making it Mg2+. Choice A (Ne2+) is incorrect because neon (Ne) has an atomic number of 10, not 12. Choice B (Ti2+) is incorrect because titanium (Ti) has an atomic number of 22, not 12. Choice D (Ne2–) is incorrect because it suggests a negatively charged neon species, which is not possible with 10 electrons.