Chemistry of Metals and Alloys

Earth's outer core is primarily composed of iron and nickel in liquid state, while the inner core is solid and almost entirely iron with some nickel. The other options (aluminium-zinc, manganese-nickel, chromium-molybdenum) are not major components of Earth's core structure.

The Earth's core (both outer and inner) is primarily composed of Nickel (Ni) and Iron (Fe), hence called the NIFE layer. This composition is responsible for Earth's magnetic field. Silica and magnesium compose the mantle, not the core.

Mercury is the toxic metal which is present in a clinical thermometer.

Lithium is the lightest metal with an atomic mass of 6.94 and density of 0.534 g/cm³. It's so light that it floats on water and is the first element in the alkali metal group. This property makes it invaluable for lightweight batteries and aerospace applications where weight reduction is critical.

German Silver is actually a copper-nickel-zinc alloy despite its name containing no silver. It's called 'German Silver' or 'Nickel Silver' because of its silver-like appearance. This alloy is corrosion-resistant and used for coins, musical instruments, and silverware as an economical alternative to actual silver.

Nichrome is a nickel-chromium alloy specifically designed for heating elements due to its high electrical resistance and ability to withstand extreme temperatures without oxidizing. It maintains structural integrity even when red-hot, making it ideal for electric heaters, toasters, and hair dryers. The resistance generates heat while the material itself remains stable.

Aluminium is the most abundant metal in Earth's crust at about 8% by mass, though it's never found free in nature. It's always combined with oxygen and other elements in compounds like bauxite. While iron is more abundant in the entire Earth (including the core), aluminium dominates the crust specifically where we can access it.

Red phosphorus is used in safety matches because it is stable and less reactive than white phosphorus. The striking surface contains red phosphorus, which reacts with the match head compounds when rubbed against it. White phosphorus is too dangerous and spontaneously ignites in air.

Mercury is the only metal that forms amalgams (alloys) with other metals at room temperature. This unique property is because mercury is liquid at room temperature and can dissolve many other metals. Amalgams have various applications, including in dentistry and gold extraction.

Gold is the most malleable metal, meaning it can be hammered into extremely thin sheets without breaking. A single gram of gold can be beaten into a sheet covering several square meters. Silver and aluminum are also malleable but not to the same extent as gold, while sodium is too reactive.

“Silver” is the metal that is present in the photo film and the reason for it is that it creates darkness on the film or photo. The developer dissolves the unreacted silver and makes the film or photo stable to light.

A more reactive metal can displace a less reactive metal from its salt solution. Magnesium is more reactive than zinc (higher in reactivity series), so it can displace zinc from zinc sulphate solution. Lead, iron, and mercury are less reactive than zinc.

Active metals like zinc can displace hydrogen from dilute acids because they are more reactive than hydrogen. Zinc reacts with dilute HCl or H2SO4 to form Zn2+ ions and hydrogen gas. Gold, copper, and silver are less reactive than hydrogen.

Gold is a noble metal, meaning it is resistant to corrosion and oxidation. Diamond is not a metal, and steel is an alloy of iron.

Aluminum is used for connecting leads in IC chips due to its excellent conductivity, low cost, and ability to form reliable wire bonds. Silicon and germanium are semiconductors used for the chip substrate, while lead is not used due to toxicity and poor bonding properties.