1 ppb means one part in 1 billion. It can be converted into
as follows:
![1 ppb=1\mu g/kg](https://img.qammunity.org/2019/formulas/chemistry/college/bvfh4gwxjcr10tgcl5wgza9gxyelfk6utc.png)
Also, 1 L is equal to 1 kg because density of water is 1 kg/L.
Thus,
![1 ppb=1\mu g/L](https://img.qammunity.org/2019/formulas/chemistry/college/3a8jfv50zttl2mntmsc356yo76z7huvcrl.png)
The arsenic level in groundwater in Bangladesh ranges from
to
. This can be converted into ppb as follows:
![200\mu g/L=200 ppb](https://img.qammunity.org/2019/formulas/chemistry/college/ki8vpuqbuh3raynqnmh5cx1bu3cc0fy0hz.png)
and,
![500\mu g/L=500 ppb](https://img.qammunity.org/2019/formulas/chemistry/college/r6ipywcbcdd41sp493gxb6ruksnirtqioj.png)
Therefore, the range in ppb is 200-500 ppb.