Which alloy is used for making bullets and lighter flints?

Misch metal

The correct answer is option 2. Misch metal.

Out of the options listed, the alloy used for making bullets and lighter flints is Misch metal.

Misch metal is a pyrophoric alloy, meaning it ignites spontaneously when exposed to air. This property makes it ideal for lighter flints. It is also a hard and dense material, which is useful for bullets. Misch metal is a mixture of rare-earth elements, typically containing around 94-95% lanthanum (La), cerium (Ce), and other lanthanides, with about 5% iron (Fe) and trace amounts of sulfur (S), carbon (C), calcium (Ca), and aluminum (Al).

Here's a breakdown of the other options:

Shell metal: This term is not a commonly used name for any specific alloy.

Gun metal: This is a historical term for a type of bronze alloy used in firearms in the past. It is not commonly used today for bullets due to the availability of better materials.

Monel metal: This is a nickel-copper alloy with high strength and corrosion resistance. It is not typically used for bullets or lighter flints.