A cutting tool is made from an alloy of metal X and element Y. The alloy is harder than pure metal X. Which statement explains why the alloy is harder?
The Y atoms form molecules with X atoms, so the molecules hold the layers in fixed positions.
The Y atoms are a different size from the X atoms, so they distort the layers and make sliding more difficult.
The Y atoms provide extra delocalised electrons, which transfer the applied force throughout the structure.
The Y atoms increase the number of regular layers, so the force is spread across more layers.
84 exam-style questions on AQA GCSE Chemistry 2.2 How bonding and structure are related to the properties of substances, covering 2.2.1a The three states of matter, 2.2.1b Limitations of the simple particle model, 2.2.2 State symbols in chemical equations, 2.2.3 Properties of ionic compounds, 2.2.4 Properties of small molecules, 2.2.5 Polymers, 2.2.6 Giant covalent structures, 2.2.7 Properties of metals and alloys, and 2.2.8 Metals as conductors. Each one has a worked solution and a mark scheme showing where the marks go.