The following are examples of chemical properties except

choices
the ability to burn

the ability to be crushed

the ability to react with oxygen

toxicity

the ability to be crushed

Explanation:

Chemical change are effects that is accompanied by changes in the chemical composition of a substance. When chemical changes occur the new substance are chemically different from the formal substance. A new chemical matter is usually formed after the change occur . Example of chemical changes are rusting of iron, toxicity, combustion(substance burning in the presence of oxygen), ability of substance to react with oxygen.

Physical changes are changes that does not alter the chemical composition of the new substance . Example of physical changes are steam condensing into liquid, sugar dissolving in water and crushing a solid substance. The changes are usually physical changes. The overall substance does not change in chemical composition.  

2fe + 3h2so4 -> fe2(so4)3 + 3h2

it is necessary to balance equations in order to get the proper amount of reactants as well as products in order not to make a miscalculation.

you cannot change the subscripts as that would change the substance itself. for instance, diatomic elements such as h2 only have the subscript two when a gas. another example would be so4, if you were to change the subscript, the element would no longer be sulfate.

we change the coefficients instead as that only changes the number of molecules rather than the substance itself.

hope this !