Question

Chromatography is used to separate:
A) molecules
B) atoms
C) solution
D) mixtures

Answer 1

Separation techniques can be physical and chemical methods. Physical separation techniques include chromatography, filtration, distillation which are based upon the physical characteristics of the materials while chemical separation techniques include crystallization, adsorption, absorption, stripping which are based upon the chemical characteristics of materials.

Complete answer:
Chromatography technique is a physical separation technique which enables separation, identification, and the purification of components of a mixture. The principle of this method states that components are made to move at different rates in a mixture or differential absorption of an absorbent. In this process, an impure substance is placed in a medium (i.e. liquid or gas). Then the medium is migrated through an absorbent. Different components of an impure substance will be absorbed at different levels. And thereafter, the absorbed components will be removed using a suitable solvent. As a result, we can say three components form the basis of this method:
Stationary phase: It is mainly composed of either a “solid” phase or “layer of a liquid adsorbed on solid support”.
Mobile phase: It always comprises either “liquid” or “gaseous component.”
Separated molecules
The interaction between the stationary phase, mobile phase, and the substances present in mixture is the basic component that is effective for the separation of molecules. Different forms of this method are available like Column Chromatography (using aluminium trioxide), Gas chromatography, Thin Layer Chromatography and all of these work on the same principle i.e. all comprise of a stationary phase as well as a mobile phase.
Hence, chromatography is used to separate mixtures. Thus, Option (D) is correct.

Note:
Chromatography is considered to be the most precise separation, analytical or purification technique that uses very low volume of sample. It has applications for a wide range of samples like drugs, plastics, food particles, pesticides, water and air samples and even tissue extracts.