<u>Answer:</u> The correct answer is geographical map.
<u>Explanation:</u>
Model is defined as the three dimensional representation of a proposed structure in a smaller scale.
For the given options:
<u>Option 1:</u> PV = nRT
This is a proposed law. This law is known as ideal gas law. A law is defined as the rule which defined a correct procedure. For any gas behaving ideally, this law is used.
<u>Option 2:</u> Geographical map
Map is defined as the diagrammatic representation of an area of land or sea which also shows physical features, roads, cities etc..
A 3-D model can be prepared for geographical map.
<u>Option 3:</u> I believe that aliens exist
This is a hypothetical statement. It is a smart guess by the means of set of assumptions and observations. For its validation, we need to conduct some experiments.
Hence, the correct answer is geographical map.
Using the method chromatography
Answer: The missing coefficient is 2.
Explanation:
According to the law of conservation of mass, mass can neither be created nor be destroyed. Thus the mass of products has to be equal to the mass of reactants. The number of atoms of each element has to be same on reactant and product side. Thus chemical equations are balanced.
As in the products, there are 2 atoms of sodium, thus there will be 2 atoms of of sodium in the reactant as well. This will balance the number of hydrogen and oxygen atoms as well.
Thus the missing coefficient is 2.
