When heating a substance in a test tube, where should you always point the open end of the tube?

• A. Directly toward yourself
• B. Straight up toward the ceiling
• C. Toward another person
• D. Away from yourself and others

Answer: (D)

Verified step by step guidance

1. Understand the safety principle behind heating substances in a test tube: when a substance is heated, it can splatter or release gases suddenly.
2. Recognize that pointing the open end of the test tube directly toward yourself or others can cause injury if hot liquid or gas is expelled.
3. Identify that the safest practice is to always point the open end of the test tube away from yourself and others to avoid accidents.
4. Note that pointing the test tube straight up toward the ceiling is not recommended because splattering can still occur and may cause harm if it falls back down.
5. Conclude that the correct safety procedure is to angle the test tube so the open end is directed away from all people during heating.