How much HBrO must be added to 1L of pure water to make a solution with a pH of 5.25?

How much HBrO must be added to 1L of pure water to make a solution with a pH of 5.25? Ka = 2.00 × 10−9 .

1. 22.7 M

2. 2810 M

3. 1.58 × 1019 M

4. 5.21 M

5. 63.2 M

6. 1.58 × 10-20 M

7. 0.0158 M correct

can you please explain how to do this question