Question 25877
SEE THE FOLLOWING EXAMPLE AND TRY.IF YOU STILL CANT GET COME BACK FOR US TO ANSWER.
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How much water must be evaporated from a 300L tank of a 2% salt solution to obtain a 5% solution?
300 LITRES OF 2% SOLUTION WILL HAVE 300*2/100=6 SALT AND 300-6 = 294 WATER.
LET X LITRES BE EVAPORATED.HENCE WE HAVE 294-X WATER.AND 6 SALT =TOTAL 300 - X LITRES.
HENCE SALT % IN THIS IS 
=6*100/(294-X)= 5 % AS GIVEN 
600/(294-X)=5
294-X=600/5=120
X=294-120 = 174
HENCE 174 LITRES ARE TO BE EVAPORATED TO GET 5% SOLUTION.