Question

1. cassandra notices that when she breathes on a cool window, the water vapor in her breath forms liquid water. what happens to turn the water vapor in her breath into liquid water?

a. heat is added to the water vapor from the surrounding air.
b. the temperature of the water vapor increases as it leaves her body.
c. the water molecules become more spread apart as they touch the window.
d. heat leaves the water vapor as it touches the cool window.

1. a controlled experiment is a means for carrying out a fair test of a hypothesis. in a controlled experiment, all of the variables that can influence the outcome variable (dependent variable) of the experiment are controlled or held constant, except for the test variable (independent variable). which of the following hypotheses would not be tested using a controlled experiment?

a. a geologists hypothesis about how the grand canyon formed.
b. a biologists hypothesis that use of fertilizer increase the growth of grass.
c. a biologists hypothesis that increases in average temperatures causes an increase in honey bee population.
d. a geologists hypothesis that acid rain weathers sedimentary rock more rapidly than igneous rock.

1. each student in a science class of 25 performed the same experiment. each student shares their data and it is recorded on a class data table. tamara compared the data that she personally collected in her experiment to the data collected by the rest of her classmates. which of the following might indicate to her that her results are valid?

a. three other classes performed the same experiment.
b. the same experiment was repeated two years in a row.
c. many other students recorded data similar to hers.
d. another student in her class reached a different conclusion.

Explanation:

• Question 7: Condensation occurs when water vapor loses heat. When the warm water vapor in breath touches the cool window, heat leaves the water vapor (exothermic process), and it changes from gas to liquid. Option A is wrong as heat is lost not added. Option B is incorrect as temperature of water vapor decreases. Option C is wrong as molecules come closer (not spread apart) during condensation.
• Question 8: A controlled experiment requires manipulating variables. The formation of the Grand Canyon is a historical event that cannot be re - created or manipulated in a controlled experiment. Fertilizer use (Option B), temperature effect on bee population (Option C), and acid rain weathering rocks (Option D) can have variables controlled (e.g., amount of fertilizer, temperature range, type of rock samples).
• Question 9: If many other students (in the same class doing the same experiment) have data similar to Tamara's, it indicates consistency. Options A and B involve other classes or years (not directly relevant to her class's data validity). Option D (different conclusion) would suggest inconsistency.

Answer:

1. D. Heat leaves the water vapor as it touches the cool window.
2. A. A geologist’s hypothesis about how the Grand Canyon formed.
3. C. Many other students recorded data similar to hers.