You are asked to test the biochemical oxygen demand of a stream in your town. After observing the BOD over a week, you calculate that the water has a BOD of 150 mg of oxygen, which is a relatively high level. This leads you to conclude that
A. the water has a high level of oxygen
B. The water is likely contaminated with high levels of pollution or waste
C. the water quality is safe for most aquatic organisms
D. The high level of oxygen demand is likely caused y natural decomposition
E. The water is safe for drinking

hey your not cool]      

there is none because earth is stationary and flat.

answer : one can design an experiment using a liquid and an additive that can be added to the liquid and observe the chemical changes in the reaction species.

one would need a beaker which is filled with a known amount of the liquid in which thermometer is placed to measure the temperature changes; after addition of the additive to the liquid solution one can note down the temperature change and find whether the reaction is endothermic or exothermic in nature. by subtracting the initial temperature value with the final temperature one can find the temperature changes.

various combinations of liquid and additive can be used. liquid in this case can be a known quantity of water and additives can be epsom salt or without epsom salt the experiment can be conducted to notice the changes. water and ice, hydrogen peroxide and dry yeast, vinegar and baking soda,etc.