c1 = 10 to the power of -3wait, how'd u get this? what values did you use for c1 and c1 3M hcl was diluted to 5M hcl

c2 = 10 to the power of -5 (using the pH formulas)

so c1/c2 = v1/v2 and the ratio was 1:100 so 10 : 1000 since volume added was 990 and initial was 10 final = 1000; 1000/10 = 100. Fits the ratio :. answer is 10 | 990