how many grams of NaCl required to prepare in 2500 ppm(w/v) NaCl 250 mL solution

Answer 1

1 ppm = 1 mg/L; therefore,
2500 ppm = 2500 mg/L.
You want 250 mL; therefore, 2500 x 250/1000 = ? mg/250 mL.
Now convert mg to grams and you have it.

Answer 2

How many grams of NaCl required to prepare 20 % (w/v) NaCl solution