Which material is extremely lightweight yet strong?

• A. Glass
• B. Ceramic
• C. Carbon fibre
• D. Wood

Answer: (C)

The key idea here is the strength-to-weight ratio—how much strength you get for each unit of weight. For something to be extremely lightweight yet strong, you want a material that delivers high strength without adding much mass. Carbon fibre excels because it’s a composite made of very strong carbon fibers in a lightweight resin. This gives it a very high tensile strength while keeping density low, so it has an excellent specific strength. It’s also very stiff and can be oriented to align with the load, boosting performance where weight savings matter most.

Other materials don’t match this combination. Glass is strong in some situations but is brittle and not as resistant to tension and impact. Ceramics are very hard and strong in compression but are brittle and heavy relative to their strength. Wood is lightweight and workably strong but varies with grain and moisture and generally cannot achieve the same strength-to-weight performance as carbon fibre.

So, for an extremely lightweight yet strong material, carbon fibre is the best choice.