chemistry for health sciences quizlet

Correct Answer: D

Rationale: The correct answer is D: 4. Significant figures are non-zero digits and zeros between them. In this case, only digits 6, 4, 2, and 8 are non-zero, making them all significant. Zeros before the first non-zero digit are not significant, so the zeros before 6 are not counted. Hence, there are 4 significant figures in the number 0006428. Choice A (7) is incorrect because it includes all digits, including the leading zeros, which are not significant. Choice B (3) is incorrect because it only considers the non-zero digits, excluding the zeros between them. Choice C (8) is incorrect because it counts all digits including leading zeros, which are not significant.

Correct Answer: A

Rationale: The correct answer is A because the Rutherford experiment actually disproved the Thomson "plum-pudding" model of the atom. Rutherford's experiment involved firing alpha particles at a thin gold foil and observing their scattering patterns. The results showed that atoms have a small, dense, positively charged nucleus, which contradicted the Thomson model. Choice B is correct as the experiment was indeed useful in determining the nuclear charge on the atom. Choice C is incorrect because Millikan's oil-drop experiment determined the charge on the electron, not just that it was a simple multiple. Choice D is incorrect as the electric discharge tube did show that electrons have a negative charge.

Correct Answer: A

Rationale: The correct answer A is determined by knowing that the atomic number of rhenium is 75. Since the element is rhenium-185, the sum of protons and neutrons must equal 185. As the atomic number is 75, the number of protons is 75. Therefore, the number of neutrons is 185 - 75 = 110. Thus, rhenium-185 has 75 protons and 110 neutrons. Choices B, C, and D are incorrect as they do not adhere to the correct number of protons and neutrons in the nucleus of rhenium-185.

Correct Answer: C

Rationale: The correct answer is C: 1 mL. When adding volumes measured in different containers, you should report the result to the least precise measurement scale, which is the 1 mL pipet in this case. The graduated cylinder measures to the nearest mL, so the total volume should be rounded to the nearest whole mL. Reporting to a decimal place of 0.01 mL or 0.1 mL would imply a level of precision greater than what the equipment can provide. Choice D is incorrect as it exceeds the maximum volume capacity of the containers and is not relevant to the precision of the measurements.

Correct Answer: C

Rationale: To convert grams to milligrams, you multiply by 1000. So, 2751.4 g * 1000 = 2751.4 mg. Therefore, choice C (275.14 mg) is correct. Choice A is incorrect as it incorrectly moves the decimal point. Choice B is incorrect as it doesn't account for the conversion factor. Choice D is incorrect as it incorrectly uses scientific notation.