Question 1: Define an alloy and explain how it differs from a pure metal.

Answer: An alloy is a mixture of two or more elements, at least one of which is a metal, formed to enhance properties like strength or corrosion resistance. Unlike pure metals, alloys have a combined structure with different properties.

Question 2: Describe the mechanism of metallic bonding in alloys.

Answer: Metallic bonding involves a lattice of metal cations surrounded by a 'sea' of delocalised electrons, allowing atoms to slide past each other while maintaining strength and conductivity. In alloys, different atoms are embedded within this electron sea, modifying properties.

Question 1: An alloy contains 70% copper and 30% zinc by mass. Calculate the mass of zinc in a 500 g sample.

Answer: 150 grams

Question 2: If an alloy has a density of 8.5 g/cm³ and a volume of 100 cm³, what is its total mass?

Answer: 850 grams

Question 1: Describe a simple experiment to test the corrosion resistance of an alloy compared to a pure metal. Include variables and safety precautions.

Answer: To test corrosion resistance, prepare samples of the alloy and pure metal. Expose them to a corrosive environment, such as saltwater, under controlled conditions. Variables include material type (independent), exposure time, and environment. Wear safety goggles, gloves, and handle chemicals carefully to prevent harm. Record the extent of corrosion after a set period.

Question 1: A sample of an alloy shows an increased hardness compared to pure aluminium. Explain how the alloying process enhances hardness and what scientific principle underlies this change.

Answer: Alloying introduces different atoms into the metal's lattice, distorting the regular structure and hindering dislocation movement. This increases hardness due to the solid solution strengthening mechanism, based on metallic bonding principles.

Question 1: Explain why stainless steel, an alloy of iron, chromium, and nickel, is used for cutlery and kitchen appliances.

Answer: Stainless steel is corrosion-resistant, durable, and easy to clean due to the chromium content forming a protective oxide layer. Its strength and corrosion resistance make it ideal for cutlery and kitchen appliances.

Question 2: Multiple choice: Which of the following correctly describes the benefit of alloying copper with zinc to produce brass?

Answer: Improves corrosion resistance and strength