The important Physical Properties of Aldehydes and ketones are given below : (1) Formaldehydes is a pungent smelling gas. Other Aldehydes or Ketones constraining up to Eleven Carbon atoms are colorless liquids while still higher members are Solids. (2) The Aldehydes and Ketones are polar compounds. Their boiling points are higher than those of Hydrocarbons of Comparable molecular masses but lower than those of corresponding alcohols of Carboxylic Acids. (3) Which the exception of lower Aldehydes which have unpleasant odors, Aldehydes and Ketones have generally pleasant smell.