What scientific tool would be the most when measuring the temperature of a substance that is undergoing a phase change? a. a spectrophotometer b. a thermometer c. the periodic table d. a scale

B. A thermometer is the scientific tool that would be the most helpful when measuring the temperature of a substance that is undergoing a phase change. A thermometer is a tool used to measure temperature, so this is obviously the correct answer. A scale measures weight, the periodic table is a list of elements and wouldn't be able to measure temperature, and spectrophotometer measures wavelength, so it cannot be applied here.