Problem 144 - A Complete Resource Book in Chemistry for JEE Main

Question

Match the following: List-I 1\. Nichrome 2\. Type metal 3\. Wood's metal 4\. Devarda's alloy List-II (i) \(\mathrm{Pb}, \mathrm{Bi}, \mathrm{Sn}, \mathrm{Cd}\) (ii) \(\mathrm{Pb}, \mathrm{Sb}, \mathrm{Sn}\) (iii) \(\mathrm{Cu}, \mathrm{Al}, \mathrm{Zn}\) (iv) \(\mathrm{Fe}, \mathrm{Ni}, \mathrm{Cr}\) The correct matching is \(\begin{array}{llll}1 & 2 & 3 & 4\end{array}\) (a) (ii) (i) (iii) (iv) (b) (iii) (iv) (ii) (i) (c) (iv) (ii) (i) (iii) (d) (iii) (iv) (i) (ii)

Step-by-Step Solution

Answer

The correct answer is (c) (iv), (ii), (i), (iii).

Step 1: Identify Composition of Nichrome

Nichrome is commonly used as a resistance wire in heating elements. It is mainly composed of Nickel (Ni), Chromium (Cr), and often Iron (Fe). The correct option in List-II that matches this composition is (iv) \( \mathrm{Fe}, \mathrm{Ni}, \mathrm{Cr} \).

Step 2: Identify Composition of Type Metal

Type metals are alloys typically used in printing. They generally consist of Lead (Pb), Antimony (Sb), and Tin (Sn). The matching option in List-II is (ii) \( \mathrm{Pb}, \mathrm{Sb}, \mathrm{Sn} \).

Step 3: Identify Composition of Wood's Metal

Wood's metal is a fusible alloy that contains Lead (Pb), Bismuth (Bi), Tin (Sn), and Cadmium (Cd). The correct matching option in List-II is (i) \( \mathrm{Pb}, \mathrm{Bi}, \mathrm{Sn}, \mathrm{Cd} \).

Step 4: Identify Composition of Devarda's Alloy

Devarda's alloy is typically used as a reducing agent and consists of Copper (Cu), Aluminum (Al), and Zinc (Zn). The corresponding match in List-II is (iii) \( \mathrm{Cu}, \mathrm{Al}, \mathrm{Zn} \).

Step 5: Arrange the Matches and Select the Correct Option

Now, based on the matches: 1. Nichrome - (iv) 2. Type metal - (ii) 3. Wood's metal - (i) 4. Devarda's alloy - (iii) The correct mapping corresponds to option (c): \[ \text{(iv), (ii), (i), (iii)} \]

Key Concepts

Nichrome Composition

Nichrome is a well-known alloy recognized for its exceptional resistance to high temperatures and excellent electrical resistance. This makes it an ideal material for heating elements in appliances like toasters and hairdryers.
Nichrome primarily consists of the following elements:

• Nickel (Ni): The main constituent, providing heat resistance and strength.
• Chromium (Cr): Added to increase corrosion resistance and hardness.
• Iron (Fe): Often included in smaller amounts to improve mechanical properties and reduce cost.

These elements combine to create an alloy that can withstand temperatures up to 1,400 °C (2552 °F), without oxidizing rapidly. When considering applications that involve high heat and potential electrical currents, nichrome becomes an excellent choice due to its durability and stability under stress.

Type Metal Alloy

Type metal alloys are primarily used in the printing industry for making hand-set metal type and in letterpress machines. The hallmark of a type metal alloy is its ability to melt at relatively low temperatures while maintaining hardness when cast.
The typical composition includes:

• Lead (Pb): The base metal known for its fluidity, helping the alloy fill intricate molds during casting.
• Antimony (Sb): Added to increase hardness and improve the metal's ability to retain fine details.
• Tin (Sn): Used to reduce brittleness and enhance the material's overall quality.

This combination allows type metal to be used effectively in precision applications requiring accuracy, durability, and sharp detail reproduction, crucial traits for the typesetting process where fonts must be clear and distinct.

Wood's Metal

Wood's metal is a fascinating material often used in safety devices like fire sprinklers, where the ability to melt at low temperatures is essential for function. It is a fusible alloy characterized by its melting point, which can be as low as 70 °C (158 °F).
The typical components of Wood’s metal are:

• Lead (Pb) and Bismuth (Bi): These provide the alloy with its low melting point.
• Tin (Sn) and Cadmium (Cd): These elements contribute to the fluidity and ease of shaping the alloy while maintaining its integrity after solidifying.

Wood’s metal exhibits unique properties, such as rapid melting and non-toxicity, due to the absence of mercury. These characteristics are important for applications where rapid response to heat is necessary without posing health hazards.

Devarda's Alloy

Devarda’s alloy plays a crucial role in qualitative and quantitative chemical analysis, especially in the determination of nitrates. Named after Italian metallurgist Arturo Devarda, it serves as a useful reducing agent.
The composition of Devarda's alloy comprises:

• Copper (Cu): Provides electrical conductivity and structural stability.
• Aluminum (Al): Acts as a reducing agent, promoting reduction reactions in chemistry.
• Zinc (Zn): Enhances the alloy's reactivity and aids in its ability to effectively reduce other compounds.

These elements together make Devarda’s alloy highly valued in laboratories worldwide. Its reactivity with substances containing nitrogen is particularly beneficial, allowing for qualitative analyses in various chemical processes.