1: which of the following is the best example of a valid hypothesis?
a. children like brand x peanut butter better than brand y peanut butter.
b. if i add substance x, then it will lower the temperature at which water freezes.
c. people should eat vegetables.
d. bananas are better for you than chocolate. 2: kobe is testing whether 100 g of substance a, 100 g of substance b, or 100 g of substance c produces more oxygen in a chemical reaction at 25°c. what is the independent variable?
a. the masses of the substances
b. the temperature of the substances
c. the amount of oxygen produced
d. the nature of the substances 3: a chemist measures the amount of mercury in sediment samples from three areas of a river (the source, the midway point, and the mouth). which of the following is the most reasonable hypothesis for the chemist's experiment?
a. if a chemical plant near the source of the river is dumping mercury, then the mercury levels should be highest at the source and lowest at the mouth.
b. if a chemical plant near the source of the river is dumping mercury, then the mercury levels should be highest at the mouth and lowest at the midway point.
c. if a chemical plant near the source of the river is dumping mercury, then the mercury levels should be highest at the mouth and lowest at the source.
d. if a chemical plant near the source of the river is dumping mercury, then the mercury levels should be the same all along the river.