Question

In class one day, a student heard the teacher say that "like dissolves like." To test this theory, she performed the following

experiment:
Four 250 mL beakers containing 100 mL of water each were placed side by side on a table.
Then, she put 50 g sodium chloride, 50 g vegetable oil, 50 g sugar, and 50 g glycerin into the first, second, third, and fourth
beakers, respectively.
Finally, she stirred each beaker for exactly 2 minutes using a different stirring rod for each beaker.
Which of the following factors was the variable in her experiment?
A. the volume of the water
B. the quantities of the substances
C. the substances that were placed in the water
D.
the time that she stirred each beaker

Answer 1

In this experiment, the variable is the substance that was placed in the water. The student performed the experiment with four different substances (sodium chloride, vegetable oil, sugar, and glycerin), and she measured the effect of each substance on the water. All other factors, such as the volume of the water and the time that she stirred each beaker, were kept constant. Therefore, the correct answer is option C: "the substances that were placed in the water."