Match each specialized metallic alloy listed on the left with its correct elemental compos… — JAMB UTME

Match each specialized metallic alloy listed on the left with its correct elemental composition and primary functional application on the right.

German SilverComposed of $\text{Cu}$ , $\text{Zn}$ , and $\text{Ni}$ ; contains no actual silver metal, offering high electrical resistance and silver-like corrosion resistance.
AlnicoComposed of $\text{Al}$ , $\text{Ni}$ , $\text{Co}$ , and $\text{Fe}$ ; displays exceptional magnetic coercivity utilized for constructing strong permanent magnets.
Type MetalComposed of $\text{Pb}$ , $\text{Sn}$ , and $\text{Sb}$ ; expands upon solidification to produce sharp, high-definition letter castings in printing presses.
Wood's MetalComposed of $\text{Bi}$ , $\text{Pb}$ , $\text{Sn}$ , and $\text{Cd}$ ; possesses an unusually low melting point (approx. $65\ ^\circ\text{C}$ ) used in automatic fire-sprinkler safety plugs.

Answer

The correct matches pair German Silver with the copper-zinc-nickel silver-free alloy, Alnico with the aluminium-nickel-cobalt-iron magnetic alloy, Type Metal with the lead-tin-antimony alloy that expands upon solidification, and Wood's Metal with the low-melting bismuth-lead-tin-cadmium fusible alloy.

Each alloy aligns strictly with its chemical formula and specialized physical property: German Silver (

\text{Cu}-\text{Zn}-\text{Ni}

) is silver-free with high resistance; Alnico (

\text{Al}-\text{Ni}-\text{Co}-\text{Fe}

) forms permanent magnets; Type Metal (

\text{Pb}-\text{Sn}-\text{Sb}

) expands upon freezing; Wood's Metal (

\text{Bi}-\text{Pb}-\text{Sn}-\text{Cd}

) melts at

65\ ^\circ\text{C}

Step-by-Step Solution

Analyze the chemical composition and key characteristic of German Silver.

German Silver consists of

\text{Cu}

\text{Zn}

, and

\text{Ni}

without any silver content, valued for high electrical resistivity and silvery appearance.

Identifying naming misnomers prevents confusing German Silver with silver-bearing precious metal alloys.

Deconstruct the constituent components and physical property of Alnico.

Alnico combines

\text{Al}

\text{Ni}

\text{Co}

, and

\text{Fe}

to form hard ferromagnetic structures.

The alloy acronym highlights its elements (

\text{Al}-\text{Ni}-\text{Co}

), which deliver superior permanent magnetic strength.

Examine the solid-phase volume change characteristic of Type Metal.

Type Metal contains

\text{Pb}

\text{Sn}

, and

\text{Sb}

; the presence of antimony induces volumetric expansion upon cooling.

While most metals shrink when freezing, antimony forces Type Metal to expand into fine matrix details during printing press type manufacture.

Evaluate the thermal melting point and application of Wood's Metal.

Wood's Metal is a eutectic combination of

\text{Bi}

\text{Pb}

\text{Sn}

, and

\text{Cd}

melting at

65\ ^\circ\text{C}

Combining four metals in specific proportions disrupts individual crystal lattice stability, dropping the melting point below

100\ ^\circ\text{C}

for safety sprinkler valves.

Key Concept

Alloy Classifications, Compositions, Phase-Change Properties, and Industrial Uses

Estimated Time:3m 0s

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