A true eutectic alloy has melting point
**Core Concept**
A eutectic alloy is a mixture of two or more substances that, when combined, exhibit a lower melting point than any of the individual components. This phenomenon occurs when the substances form a eutectic point on the phase diagram, where the mixture melts at a single temperature.
**Why the Correct Answer is Right**
The correct answer is based on the principle of eutectic behavior, which arises from the equilibrium between the liquid and solid phases of the components. In a eutectic alloy, the mixture melts at a temperature that is lower than the melting points of the individual components, due to the formation of a eutectic point on the phase diagram. This is a characteristic feature of eutectic alloys, which are often used in pharmaceutical applications, such as topical anesthetics.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because a true eutectic alloy must have a lower melting point than any of the individual components. If the melting point of the mixture is above the highest melting point of the components, it is not a eutectic alloy.
* **Option B:** This option is incorrect because a eutectic alloy does not have a melting point that is equal to the melting point of one of the individual components. The melting point of a eutectic alloy is always lower than the melting points of the components.
* **Option C:** This option is incorrect because a eutectic alloy does not have a melting point that is equal to the melting point of the mixture of two components. The melting point of a eutectic alloy is always lower than the melting points of the components.
**Clinical Pearl / High-Yield Fact**
A classic example of a eutectic alloy is the combination of lidocaine and prilocaine, which forms a eutectic mixture (EMLA) that melts at a temperature of around 15°C. This eutectic mixture is used topically to provide local anesthesia.
**Correct Answer:** C.