<u>Answer:</u> The mass of arsenic found in the sample is 0.25 mg
<u>Explanation:</u>
ppm is the amount of solute (in milligrams) present in kilogram of a solvent. It is also known as parts-per million.
To calculate the ppm of oxygen in sea water, we use the equation:

Both the masses are in grams.
We are given:
Concentration of arsenic = 5 ppm
Mass of sample = 50 g
Putting values in above equation, we get:

<u>Conversion factor used:</u> 1 g = 1000 mg
Hence, the mass of arsenic found in the sample is 0.25 mg
The second one is more concentrated as they both times with the same thing but the second one (1.5) is bigger
Counting gives an exact number and exact numbers have infinite sig figs.
<h2>Answer:</h2>
C) The scientist made an identification
<h2>Explanation:</h2>
The fingerprint is a very certain method for identifying a person, because all human beings have got unique fingerprints. Forensic laboratories have database of all citizens in the area. Hence an identification is done by the results matched with the database information. The two main categories of fingerprint matching techniques are minutiae-based matching and pattern matching and both are them are present in the given database.