PLEASE HELP!! What evidence would have been needed to refute the theory of gravity before it was proven to be a law? Write 1-2 sentences.

For the following dehydrohalogenation (e2) reaction, draw the zaitsev product(s) resulting from elimination involving c3–c4 (i.e., the carbon atoms depicted with stereobonds). show the product stereochemistry clearly. if there is more than one organic product, both products may be drawn in the same box. ignore elimination involving c3 or c4 and any carbon atom other than c4 or c3.

The excretory system,need answers for all: )

Mary is conducting an experiment on how pollution affects plant growth. how can she ensure that her data are reliable?