Mr. White gives you an empty box and asks you to push it with 10N of force. He then puts all of the class textbooks in the box, and asks you to continue pushing with 10N of force. The mass of the box and the acceleration of the box

D)can be increased in a closed system

There is no reason to think the results are biased or not conducted properly but you should not assume the results are correct just because they were done in a laboratory so the answer would be c. it is likely to be reliable because the results support the conclusion presented.

Use a magnet to separate iron, evaporate water, i'm not sure how to separate the other two i'm sorry but good luck