Question

A 4% salt concentration is equal to how many ppm?

• A. 40000
• B. 4000
• C. 400
• D. 40

Hint:

Remember that 1 percent equals 10000 ppm, since a million is ten thousand times a hundred.

Answer 1

The Correct Option is A

Step 1: Understanding the Question:
We need to convert a concentration given as a percentage (4%) into parts per million (ppm), a unit used often for reporting soil and water salinity.

Step 2: Key Formula or Approach:
Percent means parts per hundred, while ppm means parts per million. Since one million is ten thousand times bigger than one hundred (\(1{,}000{,}000 / 100 = 10{,}000\)), converting from percent to ppm just means multiplying the percentage value by 10000.
\[ \text{ppm} = \% \times 10000 \]

Step 3: Detailed Explanation:
Here the salt concentration is 4%, so applying the conversion:
\[ 4 \times 10000 = 40000 \text{ ppm} \]
This directly matches option 1. Option 2 (4000) is what you would get if you mistakenly multiplied by 1000 instead of 10000, option 3 (400) treats it as if 1% equals 100 ppm, and option 4 (40) is off by a factor of a thousand, none of these use the correct percent-to-ppm scale factor.

Step 4: Final Answer:
\[ \boxed{4\% = 40000 \text{ ppm}} \]