It is about chemistry

Question

 (a) How much the weight of Na2CO3 was used to produced 50 ppm of carbonate?

 

(b) Why buffer 9 seldom used in analysis?

Answer 1

ppm = mg/L

Thus, 50 ppm = 50 mg/L

Depending on what the total volume is, that will determine the weight of Na2CO3 was used.  So, for 1 liter, there would be 50 mg Na2CO3 and for 500 ml, there would be 25 mg of Na2CO3, etc.