'Misch metal' is an alloy widely used in the manufacture of which of the following everyday products?

Introduction / Context:
This general science question asks about a specific alloy called misch metal and its common use in daily life. Knowing typical applications of alloys helps in understanding material selection in technology and industry.

Given Data / Assumptions:

• The alloy in question is misch metal.
• Options list various products such as car brakes, smoke detectors, cigarette lighters, emergency lights and transformers.
• We are asked to identify the product for which misch metal is widely used.
• We assume standard knowledge from textbooks on alloys and their uses.

Concept / Approach:
Misch metal is an alloy of rare earth metals, primarily cerium and lanthanum, along with small amounts of other elements. It has the special property that it produces sparks when struck against a rough surface. This makes it highly suitable for use in lighter flints. Therefore, misch metal is widely used in the manufacture of the flint portion of cigarette lighters, where controlled sparking is required to ignite fuel.

Step-by-Step Solution:
1) Identify misch metal as a mixture of rare earth elements, rich in cerium.2) Recall that one of its key properties is the ability to produce a shower of hot sparks when scraped or struck.3) Consider the listed products and ask which one needs a reliable spark source as a core function.4) Cigarette lighters have a small flint that is rubbed by a rotating wheel to create sparks to ignite the fuel.5) Therefore, misch metal is most closely associated with the manufacture of flints in cigarette lighters.

Verification / Alternative check:
Standard references on alloys mention misch metal as the main component of lighter flints, often in combination with iron to make ferrocerium. When you operate a traditional lighter, the sparks you see are produced by abrasion of this misch metal based alloy. None of the other listed applications rely primarily on such sparking properties, which confirms that cigarette lighters are the intended answer.

Why Other Options Are Wrong:
Material for car brakes: Brake pads and discs are generally made from steel, cast iron or specialised friction materials, not misch metal.
Smoke detectors: These typically use small amounts of radioactive material or electronic sensors, and do not require misch metal.
Emergency lights: These depend on batteries and light sources such as LEDs or fluorescent lamps, not on spark producing alloys.
Electrical transformers: Transformers are built from copper windings and laminated iron or silicon steel cores, not misch metal.

Common Pitfalls:
Some students may wrongly associate misch metal with high strength structural applications because the name sounds technical. Others might confuse it with alloys used in car components. The key to remembering this fact is to focus on its sparking property. Any time you see a question about misch metal, think of lighter flints and sparks, which will guide you to the correct application in exams.

Final Answer:
'Misch metal' is widely used in the manufacture of flints for cigarette lighters.