Amixture of the amino acids leucine, glutamate, and arginine, is added to a cation exchange column at neutral ph. in what order will they elute from a cation exchange column

Cation-exchange chromatography is used when the molecule of interest is positively charged, the stationary phase is negatively charged and positively charged molecules are loaded to be attracted to it. So, the amino acids with negative charge will elute the first. Glutamate, leucin, arginine is the order of elution because of their pI values ~3,  ~6  ~10.

explanation:

the fossil record extends back to a dog-like ancestor some 55 million years ago, which gave rise to the first horse-like species 55 to 42 million years ago in the genus eohippus.