Add spaces: Dependingonthealtitude,theairhasadifferentdensityandadifferentchemicalcomposition.

Answer: Depending on the altitude, the air has a different density and a different chemical composition.

Add spaces: Reis'downfallcameasaresultofaflukeoffortune.

Answer: Reis' downfall came as a result of a fluke of fortune.

Add spaces: Consumerdemandfororgnicfoods:Attitudes,valuesandpurchasingbehaviour

Answer:
Consumer demand for orgnic foods : Attitudes, values and purchasing behaviour