Question

A chemical solution contains 30% water and 70% alkali what quantity of water should be added to 6 litre of solution so that the water content become 40% in

Answer 1

Quantity of water in 6 litre solution =6×30100=1.8=6×30100=1.8 litre

Suppose xx litre of water is added to the solution. Then,
total quantity of the solution =(6+x)=(6+x) litre
quantity of water =(1.8+x)=(1.8+x) litre
concentration of water = 40%

Therefore,
(6+x)40100=1.8+x(6+x)25=1.8+x2(6+x)=5(1.8+x)12+2x=9+5x3x=3x=1(6+x)40100=1.8+x(6+x)25=1.8+x2(6+x)=5(1.8+x)12+2x=9+5x3x=3x=1

Required quantity of water = 1 litre

 

Answer 2

Let the amount of water be x.

Liters

of

Percent Pure

Type Liters alkali alkali

of of as a in

liquid liquid decimal liquid

-------------------------------------------

alkali 6 0.7 6(0.7)=4.2

water x 0.0 x(0.0)= 0

-------------------------------------------

mixture 6+x 0.4 0.4(6+x)

The equation comes from the last column.

4.2 + 0 = 0.4(6+x)

Solve that and get 4.5 liters of water.

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