<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
Answer:
A. endothermic.
A. Yes, absorbed.
Explanation:
Let's consider the following thermochemical equation.
2 HgO(s) ⇒ 2 Hg(l) + O₂(g) ΔH = 182 kJ
The enthalpy of the reaction is positive (ΔH > 0), which means that the reaction is endothermic.
182 kJ are absorbed when 2 moles of HgO react (molar mass 216.59 g/mol). The heat absorbed when 72.8 g of HgO react is:

All of the above would be the answer
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