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Atoms are the basic units of matter and the defining structure of elements. We count the number of atoms by the total number of elements present in the compound. In this case, we have 1 atom of Si and 2 atoms of oxygen which would have 3 total number of atoms.
<span>35 grams
The average salinity of seawater is 35 parts per thousand, so multiply the mass of seawater provided by 0.035 and you'll get the amount of salt (mostly sodium chloride) dissolved in it. So
1000 g * 0.035 = 35 g
Therefore in 1 kilogram of seawater with average salinity, there is 35 grams of salt.</span>