Explanation

Metamorphic rocks are formed from pre-existing rocks (igneous, sedimentary, or older metamorphic rocks).

They are changed by high heat and/or pressure without melting.

Common examples include marble (from limestone) and gneiss (from granite).

The process is called metamorphism, meaning “change in form.”

Explanation

• Diamond is a naturally occurring allotropic form of carbon.
  • Allotropy means a single element can exist in more than one form with different structures and properties.
  • It is extremely hard.
  • It has a high melting point.
  • It is widely used in jewelry and cutting tools.

Additional information:

• Graphite – soft, good conductor
• Fullerenes (C60) – spherical molecules
• Carbon nanotubes – tubular, high strength
• Amorphous carbon – coal, soot
• Lonsdaleite – hexagonal diamond

Last verified on 17-01-2026

Explanation

Aluminum is a metal that can be recycled many times without losing its properties.

Additional information:

• Recycling 1 ton of aluminum saves up to 95% of the energy required to make new aluminum.
• Aluminum is widely used in cans, foils, and packaging, making it highly recyclable.

Last verified on 16-01-2026

Explanation

A mixture of two or more metals (or a metal with non-metals) is called an alloy

An alloy is made by mixing metals.

It improves strength and durability.

Steel (iron and carbon), is an example of an alloy.

Explanation

Steel is most elastic among the rubber, steel, glass and sponge.

Steel having the most steep linear stress-strain curve among all.

A stiffer material will have a higher elastic modulus.