Chromium is economically expensive.
Explanation
Chromium plating is a process of electroplating, which is an application of the chemical effects of electric current. In this process, a thin layer of chromium is deposited onto a conductive surface (usually a cheaper metal) to enhance its appearance and durability. The choice of materials in manufacturing is governed by a balance of physical properties and economic viability.
Detailed Analysis
- Chromium is too soft to maintain shape. is Incorrect: Chromium is not soft; it is actually a very hard metal. This hardness is one of the reasons it is used as a coating, as it resists scratches and wear effectively.
- Chromium is highly brittle and prone to fracture. is Incorrect: While chromium is relatively brittle compared to some other metals, this is not the primary reason for avoiding its use as a bulk material for objects like taps. Alloys could potentially mitigate mechanical issues, but the cost factor is far more significant.
- Chromium is economically expensive. is Correct: Chromium is an expensive metal. Manufacturing entire objects like car bumpers, bicycle handlebars, or bath taps solely out of chromium would be economically unviable. Instead, manufacturers use cheaper metals (such as steel or zinc alloy) to form the bulk of the object and apply a thin coating of chromium to provide the desired finish and protection at a fraction of the cost.
- Chromium reacts vigorously with water. is Incorrect: Chromium does not react vigorously with water. On the contrary, it is highly resistant to corrosion and does not rust easily, which is the specific reason it is used to coat objects that are frequently exposed to moisture.
Key Takeaway: Electroplating allows for the combination of the mechanical strength and low cost of a base metal with the superior surface properties (shine, corrosion resistance, and hardness) of an expensive coating metal like chromium.