Chemistry · Some Basic Concepts of Chemistry

A sample of drinking water was found to be severely contaminated with chloroform, \( \text{CHCl}_3 \), supposed to be carcinogenic in nature. The level of contamination was \( 15\text{ ppm} \) (by mass). Express this in per cent by mass.

1. A
   \( 1.5 \times 10^{-5}\% \)
2. B
   \( 1.5 \times 10^{-4}\% \)
3. C
   \( 1.5 \times 10^{-2}\% \)
4. D
   \( 1.5 \times 10^{-3}\% \)