Fluoride ion is poisonous in relatively low amounts: 0.2 g of f - per 70 kg body weight can cause death. nevertheless, in order to prevent tooth decay, f - ions are added to drinking water at a concentration of 1 mg of f - ion per l of water. how many liters of fluoridated drinking water would a 70 kg person have to consume in one day to reach this toxic level?
l
how many kilograms of sodium fluoride would be needed to treat a 7.75 107 gal reservoir?
kg

200 liters of fluoridated drinking water

293 kilograms of sodium fluoride

Explanation:

0.2g of fluoride ion per 70kg body weight can cause death

1mg (0.001g) of fluoride ion per liter of water prevents tooth decay

Liter of fluoridated drinking water a 70kg person would have to consume to reach the toxic level (0.2g) = 0.2g × 1L/0.001g = 200L

Volume of reservoir = 7.75×10^7gal = 7.75×10^7 × 3.7854L = 2.93×10^8L

1mg (10^-6kg) of sodium fluoride is needed to treat 1L of reservoir

Mass of sodium fluoride needed to treat 2.93×10^8L of reservoir = 2.93×10^8L × 10^-6kg/1L = 293kg

water   molecules stay close to each other through cohesion, the collective action of hydrogen bonds between water molecules. cohesion plants draw water upwards from the root through the stem's transport tubes (xylem) to the leaf. this transport occurs even in large trees and against gravity. transpiration, evaporation of water from plant leaves, creates a tension on water molecules being pulled up from the stem and roots.

water also has high (the attraction of one substance to another) properties because of its polar nature. adhesion of water molecules to plant cell walls counteract gravity while water is transported from roots to leaves.

water exhibits a very high surface tension when compared to other liquids. surface tension is a property of a liquid that holds the surface together and allows it to resist an external force. by capillary action, the water forms concave menisci inside the pores. the high surface tension of water pulls the concavity outwards, generating enough force to lift water from the roots to the leaves of plants.

thus, cohesion, along with adhesion and surface tension creates a capillary action that keeps water molecules interacting and moving through the plants out to the leaf cells.

therefore, option d) is the correct answer.

explanation:

state the principle of separating two immiscible liquids by separating funnel. describe an activity with diagram to separate a mixture of water and kerosene oil. answer: immiscible layers separate out in layers depending on their densities in separating funne