The speed of sound is greatest in:

## The reasoning Sound is a **mechanical wave** — it travels by making particles vibrate and bump into their neighbors. The speed depends on how tightly packed and connected those particles are. In **steel**, atoms are locked in a rigid lattice, incredibly close together. When one vibrates, it instantly nudges its neighbor. That's *fast* transmission — about **5,000 m/s**. In **water**, molecules are close but can slide around. Sound moves at roughly **1,500 m/s** — faster than air but slower than solids. In **air**, molecules are far apart and bounce randomly. Sound crawls at about **340 m/s**. In a **vacuum**, there are *no particles at all*. Sound cannot travel. Speed = 0 m/s. **Principle:** Sound speed increases with the stiffness and density arrangement of the medium. Solids > Liquids > Gases. ## Why the wrong options tempt you **A (Air)** — We hear sound in air daily, so it *feels* natural. But familiarity ≠ fastest. **B (Water)** — You might remember sound travels in oceans, but liquids are still looser than solids. **D (Vacuum)** — Sounds futuristic, but space is silent! ## Quick takeaway **"The tighter the particles grip each other, the faster sound flies — solids win every time."**