Astudent poses the question: how does the presence of dissolved salt affect the freezing point of water? to answer this question, the student set up two conditions. in the first condition, the student added salt to water in a container and referred to this condition as the variable. in the second condition, the student did not add any salt to water in a second container and referred to this condition as the control. the student took both containers and attempted to freeze the water at various temperatures to assess the freezing point. would this be a valid experiment?
a. yes, because there is more than one variable. b. yes, because there is one variable and a controlc. no, because there is not more than one variabled. no because there is only one variable and a control

The answer is A.

Explanation:

The example experiment given in the question would be a valid experiment because there is more than one variable.

For an experiment to be valid, there have to be a dependent variable, an independent variable, a constant and a control aspect.

In the example, we can say that the independent variable which has the direct effect on the aspect that we are looking for, the freezing point, is the amount of salt in the water. Therefore the dependent variable is the freezing point which is the part being observed for any change. The constant can be the amount of water used because it is static and the control can be the temperature the mixtures are exposed to which does not change throughout the experiment.

Therefore the answer is option A.

I hope this anwer helps.

the dna molecules have a negative charge because of the phosphate groups in their sugar-phosphate backbone, so they start moving through the matrix of the gel towards the positive pole. power is turned on and dna fragments migrate through gel (towards the positive electrode).

explanation: