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Answer: It is perhaps easiest to explain the way to get the answer by dealing with numbers. If we assume you have 10 ml of your 1% solution, then to dilute this to 0.2% (i.e. one fifth) then you would need to take 1/5 of your 1% solution, which would be in this example 1/5 of 10 = 2ml. To make up the total of 10ml, you would now need 8ml of water. Similarly, to dilute to 0.4% (i.e. two fifths), you would need 4/5 of 10 = 4ml. To make this up to the total of 10ml, you would need to add 6ml of water. This is then repeated for the concentrations you would need. Here is a table that you might find useful:
