Is the fact that table salt is composed of Na & Cl a chemical or physical property?

So I came across this question asking whether something is physical or chemical.



> 
> Table salt is composed of $\ce{Na}$ & $\ce{Cl}$. Is it a **physical** property or a
>  **chemical** property?
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I really don't understand why the answer says its a **chemical** property. I asked the others and they did not give me an understandable answer.


**Edit:** Now as I think about it, I really don't think there is an accurate answer, even if the book said it was chemical. Bad question from the book.




The problem rises when we are mistaken about what a property is. 



> 
> The different types of matter can be distinguished through two components: composition and properties. [UCDavis](http://chemwiki.ucdavis.edu/Analytical_Chemistry/Chemical_Reactions/Properties_of_Matter)
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Do a search about chemical property, and you get:



> 
> a property or characteristic of a substance that is observed during a reaction in which the chemical composition or identity of the substance is changed. [Dictionary.com](http://dictionary.reference.com/browse/chemical+property)
> 
> 
> A chemical property is any of a materials properties that becomes evident during a chemical reaction; that is, any quality that can be established only by changing a substance's chemical identity. Simply speaking, chemical properties cannot be determined just by viewing or touching the substance; the substance's internal structure must be affected for its chemical properties to be investigated. However a catalytic property would also be a chemical property. [Wikipedia](http://en.wikipedia.org/wiki/Chemical_property)
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> Any **characteristic** that can be determined only by changing a substance's molecular structure.
>  [Boundless](https://www.boundless.com/chemistry/textbooks/boundless-chemistry-textbook/introduction-to-chemistry-1/physical-and-chemical-properties-of-matter-28/physical-and-chemical-properties-of-matter-181-1817/)
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What's a physical property?



> 
> A physical property is any property that is measurable whose value describes a state of a physical system. The changes in the physical properties of a system can be used to describe its transformations or evolutions between its momentary states. Physical properties are often referred to as observables. **They are not modal properties.** - [Physical property in wikipedia](http://en.wikipedia.org/wiki/Physical_property).
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Basically, a physical property is what that doesn't deal with the composition of matter; but other factors, such as it's physical state. "Physical" isn't at its literal meaning.


Table salt is never pure $\ce{NaCl}$; because simply there's nothing pure in the nature. It's *mainly* composed of Sodium Chloride crystals. But if, and only if, we consider it to be only made from $\ce{NaCl}$, we are talking about its chemical composition and therefore, it must be a chemical property.


I understand that sometimes there are wrong questions for us to answer, so if composition is to be a property, it **must** be a chemical one.


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First, table salt is composed of $\ce {NaCl}$ wich is different from $\ce {Na}$ & $\ce{Cl}$. 


Second, actually table salt isn't exclusively composed of $\ce {NaCl}$ depending of the soure but contains also a fair amount of $\ce {KCl}$


Third, composition isn't what you can call a "property". I mean, it's a definition, compound containing only $\ce {NaCl}$ or other $\ce {KCl}$ is table salt that's all. 


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