The equation with the concentrations of the products of a reaction raised to their stoichiometric coefficients divided by the concentrations of the reactants raised to their stoichiometric coefficients.

Explanation:

This is the description of the equilibrium constant equation. For example:

Given a generic reaction:

Where A.B,C and D are the reactants and products and a,b,c and d are their stoichiometric coefficients. The equilibrium constant of this reaction will be:

Note: is important to have in mind that the substances in solid or liquid (pure) state should not be included in the K equation.

out of these options:

ability to burn paper

pure sodium reacting violently with water

the boiling point of water

helium does not tend to react with anything

i would say this is a physical property:

helium does not tend to react with anything

why? :

i said helium does not tend to react with anything because well, it reacts to ! but ability to burn paper, pure sodium reacting violently with water, & the boiling point of water are chemical or

physical properties: the properties of a substance that can be observed without changing the chemical makeup of the substance

chemical properties: properties of a substance relating to the chemical nature and reactivity of the substance