What mass of HI should be present in 0.300 L of solution to obtain a solution with each

What mass of HI should be present in 0.300 L of solution to obtain a solution with each of the following pH’s?
pH=1.25
Express your answer using two significant figures.
pH=1.75
Express your answer using two significant figures.
Part C
pH=2.85
Express your answer using two significant figures.