Classification of monosaccharides (1)According to the number of carbon atoms present in the molecule triose tetrose pentose hexose (2 )According to whether they contain an aldehyde or keto group. aldose erose ( )These two classification are frequently combined for example: C5 aldopentose ketopentose◼ Classification of Monosaccharides: (1)According to the number of carbon atoms present in the molecule. triose tetrose pentose hexose (2)According to whether they contain an aldehyde or keto group. aldose ketose (3)These two classification are frequently combined. for example : C5 aldopentose ketopentose