Describe the proper procedure for heating a test tube.

The proper procedure for heating a test tube involves holding it at an angle and heating it slowly. This method allows for safer heating of the contents within the test tube. By holding the test tube at an angle, you reduce the risk of any liquid boiling over, which could occur if the heat is applied too rapidly or directly without proper control. This technique provides a more diffuse heating pattern, allowing for even temperature distribution and minimizing the risk of breakage or unexpected reactions.

Additionally, holding the test tube with a test tube holder ensures that you are at a safe distance from the heat source and any potential fumes or splashes from the contents. This approach also allows for better observation of any reactions occurring within the test tube.

Other heating methods, such as direct flame heating without holding it or putting it in an oven, could result in uneven heating or dangerous situations where the glass could break. Submerging a test tube in ice, while useful for cooling, does not apply to heating and would not be relevant in this context.