In jewellery making, gold is usually mixed with which metal to form a harder alloy?

Introduction / Context:
Pure gold is a very soft metal, so it is rarely used alone in jewellery. Instead, it is alloyed with other metals to improve its hardness, durability, and sometimes its colour. This question tests your understanding of which metal is most commonly used to alloy gold for ornaments, an important idea in both chemistry and general awareness.

Given Data / Assumptions:

• We are dealing with gold used in jewellery, such as rings, chains, and bangles.
• Options include several common metals: zinc, tin, copper, aluminium, and lead.
• We assume standard traditional alloys like 22 carat or 18 carat gold used in everyday ornaments.
• The goal is to identify the typical alloying metal and not rare or special alloys.

Concept / Approach:
Alloys are mixtures of metals designed to give better properties than the pure metals. Pure gold (24 carat) is soft and easily scratched. To make it suitable for daily wear, it is alloyed mainly with copper and sometimes with silver. Copper increases hardness and maintains a desirable colour. Zinc, tin, aluminium, and lead are not the standard primary alloying metals for gold jewellery, especially in traditional practice.

Step-by-Step Solution:
Step 1: Recall that jewellery often uses 22 carat or 18 carat gold, which means gold is mixed with small amounts of other metals. Step 2: The most common alloy is gold plus copper, sometimes with a little silver, which gives strength and a pleasant yellow colour. Step 3: Zinc is used in some brass and galvanising applications, not as the main alloying metal with gold for ornaments. Step 4: Tin and aluminium are also not standard partners in gold jewellery alloys; they would alter physical and colour properties in less desirable ways. Step 5: Lead is toxic and very soft, so it is not suitable for ornaments that touch the skin; it is certainly not the usual alloying metal with gold. Step 6: Therefore copper is the correct answer.

Verification / Alternative check:
You can verify this from hallmarking information or basic metallurgy references. For example, red or rose gold is specifically an alloy of gold and copper. White gold is gold alloyed with metals like nickel or palladium, but even there copper may be present in small amounts. For standard yellow gold used in many countries, copper remains the main alloying metal. Practical jewellers also confirm that gold plus copper alloys are easy to work with and have long tradition.

Why Other Options Are Wrong:
Zinc: Mostly used in brass and galvanised steel, not the primary choice for gold jewellery alloys.
Tin: Used in solders and some alloys but not a major alloying element with gold for ornaments.
Aluminium: Light metal with different properties; not commonly used with gold for jewellery making.
Lead: Toxic and very soft; not suitable for jewellery and not used to alloy gold in normal practice.

Common Pitfalls:
Students sometimes think any metal can be mixed with gold. In reality, the alloy must maintain colour, lustre, and mechanical strength while being safe for contact with skin. Remember the key pairing that traditional hallmarked gold used in jewellery is usually gold mixed with copper, sometimes with silver. Knowing a few famous alloy examples like gold copper, brass (copper zinc), and bronze (copper tin) helps to avoid confusion in many general knowledge questions.

Final Answer:
In jewellery making, gold is usually mixed with copper to form a harder alloy.