RAS question
Carbon nanotubes are known for their remarkable:
Correct answer: (C) Tensile strength and electrical conductivity.
Carbon nanotubes are noted for their exceptional tensile strength and electrical conductivity.
Explanation
Carbon nanotubes are tubular, nanometre-scale arrangements of carbon atoms. NASA Spinoff describes them as carbon atoms linked by covalent bonds and rolled into a tube, with extended, uniform bonds making the material at least 117 times stronger than steel, ounce for ounce, and giving it a high degree of electrical conductivity. Carbon nanotubes show extraordinary tensile strength, roughly 50 to 100 times stronger than steel, along with excellent electrical and thermal conductivity. That combination is why option C is the substantive answer. The question is not testing nanotubes as merely magnetic, radioactive, or water-soluble materials, but as nanomaterials valued for strength and charge transport.
Why the other options are wrong
- (A) Magnetic properties may occur in some carbon nanotube contexts, but strength and conductivity are the defining properties, so 'only' makes this option too narrow.
- (B) Radioactivity is not a stated property of carbon nanotubes in NASA Spinoff or the question context, so it does not explain why CNTs are remarkable.
- (D) Pristine carbon nanotubes are hydrophobic and insoluble in water, so water solubility is the opposite of the intended property.
Concept
This tests the basic Science and Technology concept of nanomaterials and structure-property relationships. It recurs in RAS because carbon nanotubes are a standard example of how nanoscale structure can produce high strength and conductivity.