chemistry for health sciences

Correct Answer: A

Rationale: The correct answer is A: observation. Observations are specific instances of behavior that can be described and formulated into statements, including mathematical ones. Measurements (choice B) involve quantifying observations. Theories (choice C) are broader explanations based on observations. Natural laws (choice D) are general principles derived from consistent observations. In this context, the term "observed behavior" specifically points to the act of witnessing and formulating statements about behavior, making choice A the most suitable option.

Correct Answer: B

Rationale: The correct answer is B. To calculate the thickness of the monolayer, we need to use the formula thickness = density / (Avogadro's number * molecular weight). Given the density of oleic acid (895 g/mL), we can substitute this value along with the molecular weight of oleic acid into the formula. By dividing the density by the product of Avogadro's number and the molecular weight, we obtain the thickness in cm. The other choices are incorrect because they do not consider the given density and relevant constants in the calculation. Choice A, C, and D do not follow the correct formula for determining the thickness of the monolayer.

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.

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: Step-by-step rationale: 1. J.J. Thomson discovered the electron in 1897 through his cathode ray experiment. 2. Electrons are negatively charged particles emitted by atoms. 3. This groundbreaking discovery proved atoms emit negative particles. 4. Therefore, J.J. Thomson is the correct answer. Summary: - Lord Kelvin focused on thermodynamics, not subatomic particles. - Ernest Rutherford discovered the nucleus, not electrons. - William Thomson, also known as Lord Kelvin, did not directly contribute to the discovery of negative particles emitted by atoms.