Problem 54 - A Complete Resource Book in Chemistry for JEE Main

Question

Which of the following metal is found in gun metal, monel metal and constantan alloys? (a) \(\mathrm{Cu}\) (b) \(\mathrm{Fe}\) (c) \(\mathrm{Hg}\) (d) \(\mathrm{Zn}\)

Step-by-Step Solution

Answer

(a) Cu

Step 1: Understand the Alloys

Start by recalling the components of the alloys mentioned: Gun metal, Monel metal, and Constantan. Gun metal is an alloy of copper, tin, and zinc. Monel metal consists primarily of nickel and copper, while Constantan is composed of copper and nickel.

Step 2: Identify Common Element

Consider the elements listed in the options and identify which element is common in all the mentioned alloys (Gun metal, Monel metal, and Constantan). By reviewing the alloy compositions, it’s evident that copper (Cu) is a component in each of these alloys.

Step 3: Select the Correct Option

With copper identified as the common metal in all three alloys, choose (a) Cu as the correct answer from the provided options.

Key Concepts

gun metal

Gun metal is a type of bronze alloy that traditionally contains copper, tin, and zinc.
The name "gun metal" comes from its historical use in making guns and artillery.
Nowadays, it's appreciated for its strength and corrosion resistance.
This makes it a popular choice for various engineering applications, where durability is vital.
Some key features of gun metal include:

• **High Corrosion Resistance:** It withstands harsh environments, which makes it suitable for outdoor and marine equipment.
• **Good Casting Properties:** It can be easily cast into various shapes and forms without losing strength.
• **Workability:** Gun metal can be machined and worked with relative ease, making it versatile for different applications.

Understanding these features can help you see why gun metal has been a reliable material in manufacturing for centuries. Its combination of strength, ease of use, and resistance to environmental factors makes it an indispensable choice in industrial contexts.

monel metal

Monel metal is a remarkable alloy primarily composed of nickel and copper.
It's known for its impressive mechanical properties and resistance to corrosion, especially by seawater.
This makes it ideal for use in marine and chemical industries.
The composition typically involves:

• Around 65-70% Nickel
• 20-29% Copper
• Small amounts of Iron, Manganese, Carbon, and Silicon

Monel metal's key characteristics include:

• **Excellent Resistance to Corrosion:** Particularly in seawater, being a preferred choice for ships and offshore applications.
• **High Strength:** It maintains its strength over a wide range of temperatures.
• **Weldability:** Monel metals can be welded easily, making them adaptable for construction.

Understanding these properties can help in designing durable, long-lasting components for demanding environments.

constantan

Constantan is an alloy made predominantly of copper and nickel.
It's especially well known for its use in thermocouples due to a high, stable resistance and low-temperature coefficient.
The typical composition of constantan includes:

• ~55% Copper
• ~45% Nickel

Some key advantages of constantan include:

• **Stability:** It maintains a consistent resistance, which is important for precise temperature measurements.
• **Flexible Use:** Resistant to corrosion, allowing it to be used in various environments.
• **Applications in Electronics:** Common in gauges, capacitors, and resistors because of its reliable performance under varying temperatures.

With a deep understanding of constantan's composition and properties, you can appreciate its integral role in precision instrumentation and electronics.