chemistry for health sciences

Correct Answer: A

Rationale: The correct answer is A because Bromine-79 has an atomic number of 35, indicating the number of protons. Neutrons are calculated by subtracting the atomic number from the mass number, so Bromine-79 with a mass number of 79 has 44 neutrons. Electrons are equal to the number of protons in a neutral atom, so there are 35 electrons in an atom of Bromine-79. Choice B is incorrect because it does not account for the correct number of neutrons present in Bromine-79. Choice C is incorrect as it has an incorrect number of protons and electrons for Bromine-79. Choice D is incorrect as it incorrectly assigns 79 neutrons to Bromine-79, which is the total mass number, not the number of neutrons.

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: A

Rationale: To find the density in ounces/quart, we first need to convert the mass of glycerol to ounces. 2 grams is equal to 0.5 ounces (2 grams / 4 grams per ounce). Next, convert the volume from mL to quarts. Since 1000 mL is 1 liter and 1 liter is 0.26 quarts (1 liter / 3.78 liters per gallon / 4 quarts per gallon), 0 mL is equal to 0 quarts. Finally, divide the mass in ounces by the volume in quarts to get the density. Therefore, the density of glycerol is 0.5 oz/qt, which is equivalent to 41.9 oz/qt. Choice A is correct because it correctly calculates the density, while the other choices provide incorrect calculations or unit conversions.

Correct Answer: D

Rationale: The correct answer is D: Berzelius. Berzelius is credited with inventing symbols for elements and a system for writing compound formulas. He also discovered selenium, silicon, and thorium. Berzelius made significant contributions to the field of chemistry. A: Boyle is known for Boyle's Law related to gases, not for inventing chemical symbols or discovering elements. B: Lavoisier is known as the father of modern chemistry but did not invent chemical symbols or discover these elements. C: Priestly is known for discovering oxygen, but not for the specific contributions mentioned in the question.

Correct Answer: B

Rationale: To determine the significant figures in the difference between 6172 mL and 57 mL, subtract the numbers: 6172 mL - 57 mL = 6115 mL. The answer should have the same number of decimal places as the number with the fewest decimal places in the subtraction, which is 57 mL. Hence, the correct answer is 2 significant figures. Choice A is incorrect because it is too low as it does not account for the 1 in the tens place of 57 mL. Choice C is incorrect as it is too high because the answer does not have that many significant figures. Choice D is incorrect as it also overestimates the number of significant figures in the difference.