please check answer

A chemistry graduate student is given 300. mL of a 1.80M nitrous acid (HNO2) solution. Nitrous acid is a weak acid with K. = 4.5 10 -4. What mass of KNO, should the student dissolve in the HNO2 solution to turn it into a buffer with . a pH = 3.58? You may assume that the volume of the solution doesn't change when the KNO, is dissolved in it. Be sure your answer has a unit symbol, and round it to 2 significant digits. -3 37 x 10 kg X10 s