Which of the following is/are appropriate care and maintenance of centrifuges?
I. Proper balancing of centrifuge tubes.
II. Avoid long time exposure of the rotors to alkaline solution and acidic buffers.
III. Cleaning centrifuges and rotors with coarse brushes and then wash them with distilled or de-ionized water after every run.
IV. For overnight storage, the rotors are left upside down and then positioned in a safe and dry place.