Fluoridation is the process of adding fluorine compounds to drinking water to fight tooth decay. a concentration of 1 ppm of fluorine is sufficient for the purpose (1 ppm means one part per million, or 1 g of fluorine per 1 million g of water). the compound normally chosen for fluoridation is sodium fluoride, which is also added to some toothpastes. calculate the quantity of sodium fluoride in kilograms needed per year for a city of 50,000 people if the daily consumption of water per person is 150 gal. what percent of the sodium fluoride is "wasted" if each person uses only 6.0 l of water a day for drinking and cooking (sodium fluoride is 45.0 percent fluorine by mass; 1 gal= 3.79 l; 1 year =365 days; 1 ton =2000 lb; 1 lb =453.6g; density of water =1.0 g/ml)?

idk

explanation:

answer: c. the experiment shows that the red substance experienced a chemical change.

explanation: chemical change is the change in which chemical composition of the substance changes. physical change is the change in which there is no change in chemical composition.

chemical changes are accompanied by following changes:

a) precipitate formation

b) energy is released or absorbed

c) formation of bubbles

d) change in color

as it is given that the red color has disappeared and there is production of gas, it means the red substance has undergone a chemical change.

e

a boiling water reactor does not boil the water. a pressurized water reactor boils the water faster. a pressurized water reactor is heated directly by the core. a pressurized water reactor does not use fission.