Which of the following statements is/are correct? Sound waves travel through I. air II. vacuum III.Water

Analyze the question: You are asked which media sound waves can travel through: air, vacuum, or water.

Concept: Sound is a mechanical (longitudinal) wave. It is produced by vibrating particles that pass energy to neighbouring particles through compressions and rarefactions. This means sound needs a material medium (solid, liquid, or gas). Electromagnetic waves such as light and radio waves are different, because they can travel through a vacuum.

Step by step:

• I. Air: Air is a gas made of particles that can vibrate, so sound travels through it at about 330-340 m/s. ✔ Correct.
• II. Vacuum: A vacuum has no particles, so there is nothing to carry the vibrations. Sound cannot travel through it. ✘ Incorrect. (The classic experiment is the bell jar: as air is pumped out, the ringing bell becomes fainter until it is inaudible.)
• III. Water: Water is a liquid whose particles are closer together than in air, so sound travels even faster, at about 1,500 m/s. ✔ Correct.

So the correct statements are I and III only, which matches option D.

Tip: Remember "Sound needs stuff." Sound travels fastest in solids, then liquids, then gases, and it does not travel in a vacuum at all. In an exam, if "vacuum" appears as an option for sound, rule it out immediately.