The correct option is (a).
Explanation
Alloys are homogeneous mixtures of two or more metals, or a metal and a non-metal. Despite being homogeneous in nature, they are classified as mixtures rather than compounds because they retain the chemical properties of their constituent elements.
Statement-wise Analysis
- Statement 1 is Correct: Alloys are considered mixtures because they exhibit the properties of their constituent substances. For example, brass is a mixture of zinc and copper, and it shows the properties of both metals. Unlike compounds, the constituents do not lose their individual identity entirely.
- Statement 2 is Incorrect: Although alloys are mixtures, they cannot be separated into their components by simple physical methods (such as filtration, magnetic separation, or evaporation). This distinguishes them from heterogeneous mixtures, but they remain classified as mixtures due to the retention of constituent properties.
- Statement 3 is Incorrect: Alloys do not have a fixed composition. The ratio of the constituent metals can vary. For instance, the composition of brass can vary with different percentages of zinc (approximately 30%) and copper (approximately 70%) to achieve different mechanical properties.
Key Takeaway
Alloys are homogeneous mixtures that cannot be separated by physical methods, yet they are defined as mixtures because they show the properties of their constituents and can have a variable composition.