What are two equivalent measures of 3% reading of hydrogen sulfide?

To understand why the correct answer is the first option, consider the conversions of percentage to parts per million (PPM) and parts per billion (PPB). A 3% concentration of a substance means that there are 3 parts of the substance for every 100 parts of the mixture.

To find the equivalent in PPM, you multiply the percentage by 10,000. Therefore, 3% is calculated as:

3% = 3 × 10,000 = 30,000 PPM.

Next, to convert PPM into PPB, you multiply the PPM value by 1,000 since there are 1,000 parts per billion in one part per million. Thus:

30,000 PPM = 30,000 × 1,000 = 30,000,000 PPB.

Both of these conversions confirm that 3% of hydrogen sulfide is equivalently 30,000 PPM and 30,000,000 PPB.