Jax designs an experiment to determine how the amount of sodium chloride affects the boiling point of water. He adds 1 g, 5 g, and 10 g of sodium chloride to three different beakers, each containing 100 mL of water. There is a fourth beaker that contains 100 mL water without any sodium chloride. He heats each of the samples on a Bunsen burner and measures the boiling point with the same thermometer. Which of the following is/are the control(s) in the experiment? (Choose all that apply)

Amount of water

The thermometer

Explanation

In an experiment, there is always a dependent variable and an independent variable. The independent variable is manipulated and its effect on the dependent variable is observed.

The control is that factor in the experiment that must remain constant so that effect of the independent variable on the dependent variable can be observed.

In this case, the independent variable is the amount of sodium chloride while the dependent variable is the temperature at which the solution boils.

The controls must be the amount of water which must be held constant and the same thermometer used to measure the temperature so that the effect of the amount of sodium chloride on the temperature of the solution can be studied.

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