 This is the structure of cyclohexane. All the black pairs are representing the carbon atom and the white pairs are representing the hydrogen atom. It's a C6H12 and you can see these pink in color, they are representing the covalent bonds. Single covalent bonds can rotate. What you can see is the shear conformer of cyclohexane. These bonds can rotate. What will happen? They will rotate in such a manner so as to come to a more stable state. The shear conformer of cyclohexane is the most stable conformer and you can see that for example this bond is called the axial bond and this bond is called the equatorial bond. So more bulky groups like to occupy this group because let's say if there is a bulky group here, there will be no such repulsion here as you can see. If there is a bulky group here, there will be repulsion between these two bulky groups because they are closer. So that's why bulky groups tend to occupy the equatorial point. These bonds keep on rotating even at room temperature. There is enough thermal energy that they keep on flipping from chair to half chair, then to board, then again to half chair and then to chair. These clippings keep on happening at a very fast rate.