Acertain tank is filled to one quarter of its capacity with a mixture consisting of water and sodium chloride. the proportion of sodium chloride in the tank is 40% by volume and the capacity of the tank is 24 gallons. if the water evaporates from the tank at the rate of 0.5 gallons per hour, and the amount of sodium chloride stays the same, what will be the concentration of water in the mixture in 2 hours?

52 %

Explanation:

The tank is filled to one quarter its capacity

tank capacity filled with mixture = 1/4 × 24 gallons = 6 gallons

percentage of water in the mixture = 100 - 40 = 60%

60 % of 6 gallons = 3.6 gallon of water present

after two hours

the amount lost to evaporation = 0.5 gallons × 2 = 1 gallon

quantity of water remaining = 3.6 - 1 = 2.6 gallon

quantity of the mixture remaining after 1 gallon of water has been removed = 6 - 1 = 5 gallons

the concentration of water in the mixture in percentage =2.6 / 5 × 100 = 52 %  

C = 52%

Therefore, the final concentration of the mixture is 52%

Explanation:

Given;

The total capacity of the tank = 24 gallons

Rate of evaporation of water r = 0.5 gallons/hour

Time of evaporation t = 2 hours

Initial Volume of mixture in the tank V = 1/4 × 24 = 6 gallons

Initial concentration of the mixture = 40%

Volume of sodium chloride in the mixture will be given as m.

m = 40% V = 40% of 6 = 2.4 gallons

Due to the evaporation the volume of the mixture would have reduced by to V'

V' = V - rt

V' = 6 - 0.5×2

V' = 5 gallons

Since the volume of sodium chloride in the mixture is not affected by the evaporation, m remain 2.4 gallons

the final concentration of water is

C = mass/volume

C = (5.0 - 2.4)/5

C = 2.6/5

C = 52%

Therefore, the final concentration of the mixture is 52%

speed of light in vacuum is 300,000 km/s

speed of light in other mediums is given by the expression v = c/n, where c is the speed of light in vacuum and n is the refractive index of medium.

for the first medium v = 200,000 km/s

  so, refractive index of medium = 300000/200000 = 1.5

    1.5 refractive index is usually for glass. so first medium is glass.

for the second medium v = 250,00 km/s

so, refractive index of medium = 300000/250000 = 1.2

    1.2 refractive index is usually for water. so second medium is water.

for the third medium v = 0 km/s

so, refractive index of medium = 300000/0 = ∞

    ∞ refractive index is usually for opaque mediums. so third medium is opaque medium.

find the surface area of the sphere to the nearest square unit. use a calculator.

a. 254 in.2

b. 64 in.2

c. 127 in.2

d. 1,018 in.2