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:
Total Volume 
Volume of Water 
Volume of 1% concentration 
Final Concentration of solution 
10 ml 
0 ml 
10 ml 
1% 
10 ml 
1 ml 
9 ml 
0.9% 
10 ml 
2 ml 
8 ml 
0.8 % 
10 ml 
3 ml 
7 ml 
0.7% 
10 ml 
4 ml 
8 ml 
0.6% 
10 ml 
5 ml 
5 ml 
0.5% 
10 ml 
6 ml 
4 ml 
0.4% 
10 ml 
7 ml 
3 ml 
0.3% 
10 ml 
8 ml 
2 ml 
0.2% 
10 ml 
9 ml 
1 ml 
0.1% 
