a Why does a ules of ice form on the surface of a pond during freezing weather? (A) Molecules of water in the solid phase are less dense than those in the liquid phase. B Molecules of water in the solid phase are more dense than those in the liquid phase. (C) C Molecules of water in the liquid phase are less cohesive than those in the solid phase. D Molecules of water in the liquid phase are more cohesive than those in the solid phase. 9. Michael wants to test the effect of stomach acid concentration on the solubility of a particular oral medication. Which experimental design setup would best help him answer his question? (A) After allowing a pill to be exposed to one acid concentration , place it in a different acid concentration and then measure the remaining surface area. B C Using the same type of pill for each test, expose several pills to a single concentration of stomach acid and then measure the remaining surface area of each pill. Using the same type of pill for each test, expose several pills to different concentrations of stomach acid and then measure the remaining surface area of each pill. D Prepare solutions of different concentrations of stomach acid measure 50 milliliters (mL) of each into different beakers, and place different types of pills of the same mass into the beakers.

Question

a Why does a ules of ice form on the surface of a pond during freezing weather? (A) Molecules of water in the solid phase are less dense than those in the liquid phase. B Molecules of water in the solid phase are more dense than those in the liquid phase. (C) C Molecules of water in the liquid phase are less cohesive than those in the solid phase. D Molecules of water in the liquid phase are more cohesive than those in the solid phase. 9. Michael wants to test the effect of stomach acid concentration on the solubility of a particular oral medication. Which experimental design setup would best help him answer his question? (A) After allowing a pill to be exposed to one acid concentration , place it in a different acid concentration and then measure the remaining surface area. B C Using the same type of pill for each test, expose several pills to a single concentration of stomach acid and then measure the remaining surface area of each pill. Using the same type of pill for each test, expose several pills to different concentrations of stomach acid and then measure the remaining surface area of each pill. D Prepare solutions of different concentrations of stomach acid measure 50 milliliters (mL) of each into different beakers, and place different types of pills of the same mass into the beakers.

Answer 1

1. (A) Molecules of water in the solid phase are less dense than those in the liquid phase.2. (C) Using the same type of pill for each test, expose several pills to different concentrations of stomach acid and then measure the remaining surface area of each pill.

Answer 2

For the first question, ice forms on the surface of a pond because water molecules in the solid phase (ice) are less dense than in the liquid phase, causing ice to float. For the second question, to test the effect of stomach acid concentration on the solubility of a medication, Michael should use the same type of pill and expose several pills to different concentrations of stomach acid, then measure the remaining surface area of each pill to determine the effect of varying acid concentrations.

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