Answer:
Z in chemistry means atomic number but I guess there is 'Zahl'
Answer:
The concentration of impurities in the filtered water is 33 ppm.
Explanation:
Initially, the concentration of impurities is 330 ppm. If the filter removes 90% of impurities, then only 10% of the original impurities remain in the filtered water. Therefore, their concentration will be 10% of 330 ppm, that is, 33 ppm.
