A compound may be composed of different elements.
													
																	Is granite a pure chemical substance. 
									
	
		
	
																	So option b sodium chloride is a right option. 
																	A pure substance is by definition composed of one compound. 
																	So in addition to elements compounds and alloys a pure substance might include honey even though it consists of many different types of molecules. 
																	But there are exceptions to this definition. 
															
													
									
	
		
	
																	Just like granite marble is a mixture. 
																	Mixtures contain more than one chemical substance and they do not have a fixed composition. 
																	Very few samples of matter consist of pure substances. 
																	Common definition of a pure substance. 
															
													
									
	
		
	
																	A pure chemical substance is any matter that has a fixed chemical composition and characteristic properties. 
																	Pure and impure chemical substances a pure element or compound contains only one substance with no other substances mixed in. 
																	A chemical substance may well be defined as any material with a definite chemical composition in an introductory general chemistry textbook. 
																	Impure materials may be mixtures of elements mixtures of compounds. 
															
													
									
	
		
	
																	To a non chemist a pure substance is anything composed of a single type of material. 
																	Just like granite marble is a mixture. 
																	Ordinary table salt is called sodium chloride. 
																	A pure substance participates in a chemical reaction to form predictable products. 
															
													
									
	
		
	
																	However unlike granite marble is typically more than 90 calcium carbonate so it might count as a pure substance. 
																	It is considered a pure substance because it has a uniform and definite composition. 
																	A pure substance can also be defined as a form of matter that has both definite. 
																	In other words it is free of contaminants. 
															
													
									
	
		
	
																	All samples of sodium chloride are chemically identical. 
																	A pure substance or chemical substance is a material that has a constant composition is homogeneous and has consistent properties throughout the sample. 
																	Oxygen for example is a pure chemical substance that is a colorless odorless gas at 25 c. 
																	All matter consists of various elements and chemical compounds but these are often intimately mixed together.