If the [h+] changed from [1 x 10-7] to [1 x 10-4], what is the new [oh-]?
1 x 10-7
1 x 10-4
1 x 10-3
1 x 10-10

1 x 10^-10 M

Explanation:

We know that;

[H+][OH-] = 1 × 10^-14

Therefore;

when [H+] is 1 x 10^-7 then [OH-] will be;

= [1 × 10^-14]/[1 x 10^-7]

= 1 x 10^-7

When the [H+] changes from 1 x 10^-7 to  [1 x 10-4]

then the [OH-] will change from 1 x 10^-7 to;

 = [1 × 10^-14]/[1 x 10^-4]

 = 1 x 10^-10 M

Thus; the new [OH] is 1 x 10^-10 M

the ratio of the conjugate base to the acid required to attain the desired ph.