You want to place a piece of glass tubing into a rubber stopper after the tubing has been fire polished and cooled. This is best done by

When you attempt to place a piece of glass tubing into a rubber stopper after the tubing has been fire polished and cooled, you should do D. All of the above.

When inserting a piece of glass tubing that has been fire polished and cooled into a rubber stopper, you should ensure that you:

• use a towel or cotton gloves to protect yourself from any accidents with the glass as these would protect you from cuts.
• lubricate the tubing with water or glycerin so it enters the rubber stopper easily
• twist both the tubing and stopper carefully so that the tubing is secure.

In conclusion, all of the above are necessary when inserting a piece of glass tubing into a rubber stopper.

Find out more at https://brainly.com/question/17263049.

Options for this question include:

A. lubricating the tubing with water or glycerin.

B. using a towel or cotton gloves for protection.

C. twisting the tubing and stopper carefully.

D. all of the above