Chemistry of Metals and Alloys

Tungsten has the highest melting point of all metals (3422°C) and remains solid at the extremely high temperatures inside an operating bulb. Copper, iron, and aluminum would melt quickly.

Tungsten is used for electric bulb filaments because it has the highest melting point (3422°C) among all metals, allowing it to withstand the intense heat without melting. It also has high tensile strength and low vapor pressure at operating temperatures, making it ideal for long-lasting illumination. Tungsten's resistance causes it to glow white-hot when current flows through it.

Steel is the most elastic material among the options because it has the highest Young's modulus (approximately 200 GPa), meaning it requires the most stress to produce a given strain. Elasticity is the ability to return to original shape after deformation - steel deforms very little under load. Rubber is highly flexible (extensible) but not elastic in this technical sense.

Lead is commonly used for containers holding strong acids because it forms an insoluble protective layer of lead sulfate on contact with sulfuric acid, preventing further reaction. Platinum is also acid-resistant but prohibitively expensive. Copper and brass readily react with acids.

Mercury is the only metal in liquid form.

Iron is an element.

Lead dioxide (PbO2) is used as the active material in the positive plates of lead storage batteries (lead-acid batteries). It undergoes reduction during discharge, converting to lead sulfate.

The largest consumer of tellurium is metallurgy, where it is used in iron, copper and lead alloys. When added to stainless steel and copper it makes these metals more machinable.

Stainless steel contains at least 10.5% chromium, which forms a protective oxide layer on the surface. This layer prevents corrosion and gives stainless steel its rust-resistant properties. Nickel and molybdenum are often added too.

There are many different bronze alloys, but modern bronze is 88% copper and 12% tin.

All the given metal and alloy pairs are correct. The given alloys are made up by combining these metals with some other metals.

Sodium is a soft metal. It can be easily cut into pieces using a knife.

The reactivity series is a series of metals, in order of reactivity from the highest to the lowest. In this series, zinc lies in between magnesium and lead.

Mercury is a bad conductor of heat.

Both Co₃O₄ and MgAl₂O₄ are normal spinels.