Yes it is due to refraction of light in water
Mass of Magnesium nitrate produced : 593.2 g
<h3>Further explanation</h3>
The reaction equation is the chemical formula of reagents and product substances
A reaction coefficient is a number in the chemical formula of a substance involved in the reaction equation. The reaction coefficient is useful for equalizing reagents and products.
Reaction
2HNO₃ + Mg(OH)₂ → Mg(NO₃)₂ + 2H₂0
mol HNO₃ = 8
From the equation, mol ratio of HNO₃ : Mg(NO₃)₂ = 2 : 1, so mol Mg(NO₃)₂ :

Mass Mg(NO₃)₂(MW=148,3 g/mol) :

The subscriot 2 means that in the formula there are two parts of K, and the subscript 1 (implicit) for S, indicates that there is one part of S.
This is, the formula gives the ratio of the elements K and S in the compound, which is:
2 atoms of K : 1 atom of S.
Answer: there are 2 atoms of K and 1 atom of S in a molecule of K2S.