Answer:
c. It is incorrect because sodium phosphate is a compound that has a single composition.
Step-by-step explanation:
As we know that the sodium phosphate i.e. chemical compounds comprise of atoms that are interconnected with the bonds of the chemicals
Also the pure substance that is made by only and only one atom or element or only one type of molecule i.e. compound that contains definite and constant composition with different properties of chemicals
the pure substances could be distinct in chemical way but not in the physical manner that represents the difference between the mixture and the pure substance
Hence, the correct option is c.