Which device is a large beaker of water heated on a hot plate used to heat test tubes containing flammable liquids?

• A. Hot Plate
• B. Test Tube
• C. Swab
• D. Hot Water Bath

Answer: (D)

Safe, controlled heating of flammable liquids is achieved with a hot water bath. The large beaker of water, heated on a hot plate, surrounds the test tubes so heat is transferred through water rather than from an open flame or direct contact with a hot surface. This method provides even heating and helps prevent vapors from reaching ignition temperature. A hot plate alone would heat directly and can be riskier with flammable vapors; a test tube is merely the container being heated; a swab is a sampling tool.