Norman thinks that the brain function of students suffers when they receive less sleep. He predicts that students who get less sleep before an exam will receive lower test grades. To investigate his idea, he tests two groups of chemistry students. Group 1 receives four hours of sleep, while Group 2 receives the recommended eight hours of sleep the night before the exam. Both groups consume the same foods before testing. They then take the same exam in the same room. What experimental factors could have been a possible source of error in Norman's investigation? A. the amount of sleep students received before the exam. B. the temperature and light of the testing room
C. the grades students earned on their exam
D the food students consumed before the exam

ill try to . no promises tho.

explanation:

when [oh-] is 10-5  m, and [h3o+] is 10-9  m, the poh is 5 and ph is 9. again in both cases the sum of ph and poh is 14. however, the hydrogen ion concentration is not always going to be equal to exactly 1 x 10 raised to a negative number. for example, we skipped over the value of 2.0 x 10-7.

it's c. elements are placed in rows based on how may valencies electrons have.

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.