The correct answer is: B. Nano structure of carbon
Graphene is a single layer of carbon atoms arranged in a hexagonal lattice. It is the thinnest material known to man, and it is also one of the strongest. Graphene has a number of unique properties, including high electrical conductivity, high thermal conductivity, and high mechanical strength. It is also transparent and flexible.
Graphene is a promising material for a variety of applications, including electronics, energy storage, and composites. It is also being studied as a possible treatment for cancer.
A. An alloy of carbon is a mixture of two or more elements, at least one of which is carbon. Alloys are typically made by melting the constituent elements together and then cooling them slowly.
C. An isotope of carbon is a variant of the chemical element carbon that has a different number of neutrons in its nucleus. The most common isotope of carbon is carbon-12, which has 6 neutrons in its nucleus. Other isotopes of carbon include carbon-13, which has 7 neutrons, and carbon-14, which has 8 neutrons.
D. None of the above is a correct answer.