Which of the following is more tougher, lighter in weight and has better conductivity?

Carbon nanotubes

The answer is carbon nanotubes. It is the toughest, lightest, and has the best conductivity among the four materials.

• Iron is a strong and ductile metal, but it is not as tough as carbon nanotubes

• Copper is a good conductor of electricity, but it is not as light as carbon nanotubes.

• Tungsten is the densest metal, but it is not as tough or as light as carbon nanotubes.

Here is a table of the properties of the four materials:

Carbon nanotubes are also very strong and can be used to make lightweight and strong materials. They are also being studied for use in electronic devices, such as transistors and solar cells.

However, carbon nanotubes are also very expensive to produce and are not yet widely used.