15.
									
										Which of the following is not a use for mass spectrometry ? 
									
								
															
														
																									
										A:
											Calculating the isotopic abundance in elements 
									
																										
										B:
											 investigating the elemental composition of planets  
									
																										
										C:
											confirming the presence of O-H and C=O in organic compounds 
									
																										
										D:
											 calculating the molecular mass of organic compounds
									
																								 
							
																
									The answer is:
										C
									
								
														
							
								
								
							
							
							
								