Mixtures have a ... melting and boiling points.

• A. Fixed
• B. Range of
• C. Single
• D. Consistent

Answer: (B)

Mixtures contain different substances, each with its own melting and boiling temperatures, so there isn’t a single fixed temperature. As you heat a mixture, the component with the lowest melting point starts to melt first and others follow over a span of temperatures, giving a melting range. The same happens with boiling because components boil at different temperatures, so the boiling point of the mixture occurs over a range rather than at one exact temperature. In contrast, a pure substance has a precise melting point and a precise boiling point at a given pressure, which is why mixtures show a range of temperatures.